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Algebra of Complex Numbers

Mathematics · FE Reference Handbook section

Mathematics
23 formulas
10 exam-style examples
~60 min
All Mathematics lectures

Handbook notes for this section

Definitions and conditions exactly as the handbook states them.

  • Complex numbers may be designated in rectangular form or polar form. In rectangular form, a complex number is written in
  • terms of its real and imaginary components.
  • Complex numbers can be added and subtracted in rectangular form. If
  • While complex numbers can be multiplied or divided in rectangular form, it is more convenient to perform these operations in

Core formulas for this FE topic

Definitions, applicability, units, assumptions and worked examples for each relation.

Worked exam-style examples

The four ways this section is written on the real exam — thoughts first, then equations, then substitution.

Example 1
Slope–intercept line — solve for y-value — Algebra of Complex Numbers

A mathematics problem uses Slope–intercept line. Given slope (m) = 2.4000; x-value (x) = 3.5000; intercept (b) = 10.0000, determine the y-value (y).

Given

  • slope(m)=2.4000slope (m) = 2.4000
  • x−value(x)=3.5000x-value (x) = 3.5000
  • intercept(b)=10.0000intercept (b) = 10.0000

Find

y-value (y)

Start with the thinking

  • The governing relation printed in this handbook section is Slope–intercept line.
  • Everything except y is given, so isolate y symbolically first — never rearrange after the numbers are in.
  • Tabulate each given with its unit and confirm the units are consistent with the relation before substituting.
  • Mathematics items reward recognising the unknown before touching a calculator.

Step-by-step solution

  1. Step 1 — State the governing relation:

    y=mx+by = m x + b
  2. Step 2 — Rearrange the relation so that y stands alone on the left-hand side.

  3. Step 3

    Listthegivens:slope(m)=2.4000,x−value(x)=3.5000,intercept(b)=10.0000List the givens: slope (m) = 2.4000, x-value (x) = 3.5000, intercept (b) = 10.0000
  4. Step 4 — Substitute the given values into the rearranged relation.

  5. Step 5 — Evaluate:

    y=18.4000y = 18.4000
  6. Step 6 — Check: returning y = 18.4000 to

    y=mx+by = m x + b

    reproduces the given quantities, and both sides carry the same units.

Answer:
y=18.4000y = 18.4000

Why the other options are there

  • 36.8000 — kept a factor of two that cancels in the correct rearrangement.
  • 9.2000 — dropped that same factor in the other direction.
  • 20.2400 — rounded an intermediate value before the final step.

Reference: FE Reference Handbook — Mathematics → Algebra of Complex Numbers

Example 2
Slope–intercept line — solve for slope — Algebra of Complex Numbers (2)

A mathematics problem uses Slope–intercept line. Given x-value (x) = 8.5000; intercept (b) = 7.5000; y-value (y) = 46.8000, determine the slope (m).

Given

  • x−value(x)=8.5000x-value (x) = 8.5000
  • intercept(b)=7.5000intercept (b) = 7.5000
  • y−value(y)=46.8000y-value (y) = 46.8000

Find

slope (m)

Start with the thinking

  • The governing relation printed in this handbook section is Slope–intercept line.
  • Everything except m is given, so isolate m symbolically first — never rearrange after the numbers are in.
  • Tabulate each given with its unit and confirm the units are consistent with the relation before substituting.
  • Mathematics items reward recognising the unknown before touching a calculator.

Step-by-step solution

  1. Step 1 — State the governing relation:

    y=mx+by = m x + b
  2. Step 2 — Rearrange the relation so that m stands alone on the left-hand side.

  3. Step 3

    Listthegivens:x−value(x)=8.5000,intercept(b)=7.5000,y−value(y)=46.8000List the givens: x-value (x) = 8.5000, intercept (b) = 7.5000, y-value (y) = 46.8000
  4. Step 4 — Substitute the given values into the rearranged relation.

  5. Step 5 — Evaluate:

    m=4.6235m = 4.6235
  6. Step 6 — Check: returning m = 4.6235 to

    y=mx+by = m x + b

    reproduces the given quantities, and both sides carry the same units.

Answer:
m=4.6235m = 4.6235

Why the other options are there

  • 9.2471 — kept a factor of two that cancels in the correct rearrangement.
  • 2.3118 — dropped that same factor in the other direction.
  • 5.0859 — rounded an intermediate value before the final step.

Reference: FE Reference Handbook — Mathematics → Algebra of Complex Numbers

Example 3
Slope–intercept line — solve for intercept — Algebra of Complex Numbers (3)

A mathematics problem uses Slope–intercept line. Given slope (m) = 1.0000; x-value (x) = 7.0000; y-value (y) = 1.6000, determine the intercept (b).

Given

  • slope(m)=1.0000slope (m) = 1.0000
  • x−value(x)=7.0000x-value (x) = 7.0000
  • y−value(y)=1.6000y-value (y) = 1.6000

Find

intercept (b)

Start with the thinking

  • The governing relation printed in this handbook section is Slope–intercept line.
  • Everything except b is given, so isolate b symbolically first — never rearrange after the numbers are in.
  • Tabulate each given with its unit and confirm the units are consistent with the relation before substituting.
  • Mathematics items reward recognising the unknown before touching a calculator.

Step-by-step solution

  1. Step 1 — State the governing relation:

    y=mx+by = m x + b
  2. Step 2 — Rearrange the relation so that b stands alone on the left-hand side.

  3. Step 3

    Listthegivens:slope(m)=1.0000,x−value(x)=7.0000,y−value(y)=1.6000List the givens: slope (m) = 1.0000, x-value (x) = 7.0000, y-value (y) = 1.6000
  4. Step 4 — Substitute the given values into the rearranged relation.

  5. Step 5 — Evaluate:

    b=−5.4000b = -5.4000
  6. Step 6 — Check: returning b = -5.4000 to

    y=mx+by = m x + b

    reproduces the given quantities, and both sides carry the same units.

Answer:
b=−5.4000b = -5.4000

Why the other options are there

  • -10.8000 — kept a factor of two that cancels in the correct rearrangement.
  • -2.7000 — dropped that same factor in the other direction.
  • -5.9400 — rounded an intermediate value before the final step.

Reference: FE Reference Handbook — Mathematics → Algebra of Complex Numbers

Example 4
Slope–intercept line — solve for x-value — Algebra of Complex Numbers (4)

A mathematics problem uses Slope–intercept line. Given slope (m) = 4.8000; intercept (b) = -7.5000; y-value (y) = -19.2000, determine the x-value (x).

Given

  • slope(m)=4.8000slope (m) = 4.8000
  • intercept(b)=−7.5000intercept (b) = -7.5000
  • y−value(y)=−19.2000y-value (y) = -19.2000

Find

x-value (x)

Start with the thinking

  • The governing relation printed in this handbook section is Slope–intercept line.
  • Everything except x is given, so isolate x symbolically first — never rearrange after the numbers are in.
  • Tabulate each given with its unit and confirm the units are consistent with the relation before substituting.
  • Mathematics items reward recognising the unknown before touching a calculator.

Step-by-step solution

  1. Step 1 — State the governing relation:

    y=mx+by = m x + b
  2. Step 2 — Rearrange the relation so that x stands alone on the left-hand side.

  3. Step 3

    Listthegivens:slope(m)=4.8000,intercept(b)=−7.5000,y−value(y)=−19.2000List the givens: slope (m) = 4.8000, intercept (b) = -7.5000, y-value (y) = -19.2000
  4. Step 4 — Substitute the given values into the rearranged relation.

  5. Step 5 — Evaluate:

    x=−2.4375x = -2.4375
  6. Step 6 — Check: returning x = -2.4375 to

    y=mx+by = m x + b

    reproduces the given quantities, and both sides carry the same units.

Answer:
x=−2.4375x = -2.4375

Why the other options are there

  • -4.8750 — kept a factor of two that cancels in the correct rearrangement.
  • -1.2188 — dropped that same factor in the other direction.
  • -2.6813 — rounded an intermediate value before the final step.

Reference: FE Reference Handbook — Mathematics → Algebra of Complex Numbers

Example 5
Slope–intercept line — solve for y-value (case 2) — Algebra of Complex Numbers (5)

A mathematics problem uses Slope–intercept line. Given slope (m) = 4.3000; x-value (x) = 3.0000; intercept (b) = -7.5000, determine the y-value (y).

Given

  • slope(m)=4.3000slope (m) = 4.3000
  • x−value(x)=3.0000x-value (x) = 3.0000
  • intercept(b)=−7.5000intercept (b) = -7.5000

Find

y-value (y)

Start with the thinking

  • The governing relation printed in this handbook section is Slope–intercept line.
  • Everything except y is given, so isolate y symbolically first — never rearrange after the numbers are in.
  • Tabulate each given with its unit and confirm the units are consistent with the relation before substituting.
  • Mathematics items reward recognising the unknown before touching a calculator.

Step-by-step solution

  1. Step 1 — State the governing relation:

    y=mx+by = m x + b
  2. Step 2 — Rearrange the relation so that y stands alone on the left-hand side.

  3. Step 3

    Listthegivens:slope(m)=4.3000,x−value(x)=3.0000,intercept(b)=−7.5000List the givens: slope (m) = 4.3000, x-value (x) = 3.0000, intercept (b) = -7.5000
  4. Step 4 — Substitute the given values into the rearranged relation.

  5. Step 5 — Evaluate:

    y=5.4000y = 5.4000
  6. Step 6 — Check: returning y = 5.4000 to

    y=mx+by = m x + b

    reproduces the given quantities, and both sides carry the same units.

Answer:
y=5.4000y = 5.4000

Why the other options are there

  • 10.8000 — kept a factor of two that cancels in the correct rearrangement.
  • 2.7000 — dropped that same factor in the other direction.
  • 5.9400 — rounded an intermediate value before the final step.

Reference: FE Reference Handbook — Mathematics → Algebra of Complex Numbers

Example 6
Slope–intercept line — solve for slope (case 2) — Algebra of Complex Numbers (6)

A mathematics problem uses Slope–intercept line. Given x-value (x) = 9.0000; intercept (b) = -0.5000; y-value (y) = 29.8000, determine the slope (m).

Given

  • x−value(x)=9.0000x-value (x) = 9.0000
  • intercept(b)=−0.5000intercept (b) = -0.5000
  • y−value(y)=29.8000y-value (y) = 29.8000

Find

slope (m)

Start with the thinking

  • The governing relation printed in this handbook section is Slope–intercept line.
  • Everything except m is given, so isolate m symbolically first — never rearrange after the numbers are in.
  • Tabulate each given with its unit and confirm the units are consistent with the relation before substituting.
  • Mathematics items reward recognising the unknown before touching a calculator.

Step-by-step solution

  1. Step 1 — State the governing relation:

    y=mx+by = m x + b
  2. Step 2 — Rearrange the relation so that m stands alone on the left-hand side.

  3. Step 3

    Listthegivens:x−value(x)=9.0000,intercept(b)=−0.5000,y−value(y)=29.8000List the givens: x-value (x) = 9.0000, intercept (b) = -0.5000, y-value (y) = 29.8000
  4. Step 4 — Substitute the given values into the rearranged relation.

  5. Step 5 — Evaluate:

    m=3.3667m = 3.3667
  6. Step 6 — Check: returning m = 3.3667 to

    y=mx+by = m x + b

    reproduces the given quantities, and both sides carry the same units.

Answer:
m=3.3667m = 3.3667

Why the other options are there

  • 6.7333 — kept a factor of two that cancels in the correct rearrangement.
  • 1.6833 — dropped that same factor in the other direction.
  • 3.7033 — rounded an intermediate value before the final step.

Reference: FE Reference Handbook — Mathematics → Algebra of Complex Numbers

Example 7
Slope–intercept line — solve for intercept (case 2) — Algebra of Complex Numbers (7)

A mathematics problem uses Slope–intercept line. Given slope (m) = 3.3000; x-value (x) = 9.5000; y-value (y) = -12.2000, determine the intercept (b).

Given

  • slope(m)=3.3000slope (m) = 3.3000
  • x−value(x)=9.5000x-value (x) = 9.5000
  • y−value(y)=−12.2000y-value (y) = -12.2000

Find

intercept (b)

Start with the thinking

  • The governing relation printed in this handbook section is Slope–intercept line.
  • Everything except b is given, so isolate b symbolically first — never rearrange after the numbers are in.
  • Tabulate each given with its unit and confirm the units are consistent with the relation before substituting.
  • Mathematics items reward recognising the unknown before touching a calculator.

Step-by-step solution

  1. Step 1 — State the governing relation:

    y=mx+by = m x + b
  2. Step 2 — Rearrange the relation so that b stands alone on the left-hand side.

  3. Step 3

    Listthegivens:slope(m)=3.3000,x−value(x)=9.5000,y−value(y)=−12.2000List the givens: slope (m) = 3.3000, x-value (x) = 9.5000, y-value (y) = -12.2000
  4. Step 4 — Substitute the given values into the rearranged relation.

  5. Step 5 — Evaluate:

    b=−43.5500b = -43.5500
  6. Step 6 — Check: returning b = -43.5500 to

    y=mx+by = m x + b

    reproduces the given quantities, and both sides carry the same units.

Answer:
b=−43.5500b = -43.5500

Why the other options are there

  • -87.1000 — kept a factor of two that cancels in the correct rearrangement.
  • -21.7750 — dropped that same factor in the other direction.
  • -47.9050 — rounded an intermediate value before the final step.

Reference: FE Reference Handbook — Mathematics → Algebra of Complex Numbers

Example 8
Slope–intercept line — solve for x-value (case 2) — Algebra of Complex Numbers (8)

A mathematics problem uses Slope–intercept line. Given slope (m) = 4.8000; intercept (b) = 5.5000; y-value (y) = 9.7000, determine the x-value (x).

Given

  • slope(m)=4.8000slope (m) = 4.8000
  • intercept(b)=5.5000intercept (b) = 5.5000
  • y−value(y)=9.7000y-value (y) = 9.7000

Find

x-value (x)

Start with the thinking

  • The governing relation printed in this handbook section is Slope–intercept line.
  • Everything except x is given, so isolate x symbolically first — never rearrange after the numbers are in.
  • Tabulate each given with its unit and confirm the units are consistent with the relation before substituting.
  • Mathematics items reward recognising the unknown before touching a calculator.

Step-by-step solution

  1. Step 1 — State the governing relation:

    y=mx+by = m x + b
  2. Step 2 — Rearrange the relation so that x stands alone on the left-hand side.

  3. Step 3

    Listthegivens:slope(m)=4.8000,intercept(b)=5.5000,y−value(y)=9.7000List the givens: slope (m) = 4.8000, intercept (b) = 5.5000, y-value (y) = 9.7000
  4. Step 4 — Substitute the given values into the rearranged relation.

  5. Step 5 — Evaluate:

    x=0.8750x = 0.8750
  6. Step 6 — Check: returning x = 0.8750 to

    y=mx+by = m x + b

    reproduces the given quantities, and both sides carry the same units.

Answer:
x=0.8750x = 0.8750

Why the other options are there

  • 1.7500 — kept a factor of two that cancels in the correct rearrangement.
  • 0.4375 — dropped that same factor in the other direction.
  • 0.9625 — rounded an intermediate value before the final step.

Reference: FE Reference Handbook — Mathematics → Algebra of Complex Numbers

Example 9
Slope–intercept line — solve for y-value (case 3) — Algebra of Complex Numbers (9)

A mathematics problem uses Slope–intercept line. Given slope (m) = 2.4000; x-value (x) = 9.0000; intercept (b) = -8.0000, determine the y-value (y).

Given

  • slope(m)=2.4000slope (m) = 2.4000
  • x−value(x)=9.0000x-value (x) = 9.0000
  • intercept(b)=−8.0000intercept (b) = -8.0000

Find

y-value (y)

Start with the thinking

  • The governing relation printed in this handbook section is Slope–intercept line.
  • Everything except y is given, so isolate y symbolically first — never rearrange after the numbers are in.
  • Tabulate each given with its unit and confirm the units are consistent with the relation before substituting.
  • Mathematics items reward recognising the unknown before touching a calculator.

Step-by-step solution

  1. Step 1 — State the governing relation:

    y=mx+by = m x + b
  2. Step 2 — Rearrange the relation so that y stands alone on the left-hand side.

  3. Step 3

    Listthegivens:slope(m)=2.4000,x−value(x)=9.0000,intercept(b)=−8.0000List the givens: slope (m) = 2.4000, x-value (x) = 9.0000, intercept (b) = -8.0000
  4. Step 4 — Substitute the given values into the rearranged relation.

  5. Step 5 — Evaluate:

    y=13.6000y = 13.6000
  6. Step 6 — Check: returning y = 13.6000 to

    y=mx+by = m x + b

    reproduces the given quantities, and both sides carry the same units.

Answer:
y=13.6000y = 13.6000

Why the other options are there

  • 27.2000 — kept a factor of two that cancels in the correct rearrangement.
  • 6.8000 — dropped that same factor in the other direction.
  • 14.9600 — rounded an intermediate value before the final step.

Reference: FE Reference Handbook — Mathematics → Algebra of Complex Numbers

Example 10
Slope–intercept line — solve for slope (case 3) — Algebra of Complex Numbers (10)

A mathematics problem uses Slope–intercept line. Given x-value (x) = 7.0000; intercept (b) = -2.0000; y-value (y) = 23.5000, determine the slope (m).

Given

  • x−value(x)=7.0000x-value (x) = 7.0000
  • intercept(b)=−2.0000intercept (b) = -2.0000
  • y−value(y)=23.5000y-value (y) = 23.5000

Find

slope (m)

Start with the thinking

  • The governing relation printed in this handbook section is Slope–intercept line.
  • Everything except m is given, so isolate m symbolically first — never rearrange after the numbers are in.
  • Tabulate each given with its unit and confirm the units are consistent with the relation before substituting.
  • Mathematics items reward recognising the unknown before touching a calculator.

Step-by-step solution

  1. Step 1 — State the governing relation:

    y=mx+by = m x + b
  2. Step 2 — Rearrange the relation so that m stands alone on the left-hand side.

  3. Step 3

    Listthegivens:x−value(x)=7.0000,intercept(b)=−2.0000,y−value(y)=23.5000List the givens: x-value (x) = 7.0000, intercept (b) = -2.0000, y-value (y) = 23.5000
  4. Step 4 — Substitute the given values into the rearranged relation.

  5. Step 5 — Evaluate:

    m=3.6429m = 3.6429
  6. Step 6 — Check: returning m = 3.6429 to

    y=mx+by = m x + b

    reproduces the given quantities, and both sides carry the same units.

Answer:
m=3.6429m = 3.6429

Why the other options are there

  • 7.2857 — kept a factor of two that cancels in the correct rearrangement.
  • 1.8214 — dropped that same factor in the other direction.
  • 4.0071 — rounded an intermediate value before the final step.

Reference: FE Reference Handbook — Mathematics → Algebra of Complex Numbers

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