Algebra of Complex Numbers
Mathematics · FE Reference Handbook section
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.
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
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
Step 1 — State the governing relation:
Step 2 — Rearrange the relation so that y stands alone on the left-hand side.
Step 3
Step 4 — Substitute the given values into the rearranged relation.
Step 5 — Evaluate:
Step 6 — Check: returning y = 18.4000 to
reproduces the given quantities, and both sides carry the same units.
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
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
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
Step 1 — State the governing relation:
Step 2 — Rearrange the relation so that m stands alone on the left-hand side.
Step 3
Step 4 — Substitute the given values into the rearranged relation.
Step 5 — Evaluate:
Step 6 — Check: returning m = 4.6235 to
reproduces the given quantities, and both sides carry the same units.
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
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
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
Step 1 — State the governing relation:
Step 2 — Rearrange the relation so that b stands alone on the left-hand side.
Step 3
Step 4 — Substitute the given values into the rearranged relation.
Step 5 — Evaluate:
Step 6 — Check: returning b = -5.4000 to
reproduces the given quantities, and both sides carry the same units.
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
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
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
Step 1 — State the governing relation:
Step 2 — Rearrange the relation so that x stands alone on the left-hand side.
Step 3
Step 4 — Substitute the given values into the rearranged relation.
Step 5 — Evaluate:
Step 6 — Check: returning x = -2.4375 to
reproduces the given quantities, and both sides carry the same units.
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
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
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
Step 1 — State the governing relation:
Step 2 — Rearrange the relation so that y stands alone on the left-hand side.
Step 3
Step 4 — Substitute the given values into the rearranged relation.
Step 5 — Evaluate:
Step 6 — Check: returning y = 5.4000 to
reproduces the given quantities, and both sides carry the same units.
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
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
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
Step 1 — State the governing relation:
Step 2 — Rearrange the relation so that m stands alone on the left-hand side.
Step 3
Step 4 — Substitute the given values into the rearranged relation.
Step 5 — Evaluate:
Step 6 — Check: returning m = 3.3667 to
reproduces the given quantities, and both sides carry the same units.
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
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
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
Step 1 — State the governing relation:
Step 2 — Rearrange the relation so that b stands alone on the left-hand side.
Step 3
Step 4 — Substitute the given values into the rearranged relation.
Step 5 — Evaluate:
Step 6 — Check: returning b = -43.5500 to
reproduces the given quantities, and both sides carry the same units.
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
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
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
Step 1 — State the governing relation:
Step 2 — Rearrange the relation so that x stands alone on the left-hand side.
Step 3
Step 4 — Substitute the given values into the rearranged relation.
Step 5 — Evaluate:
Step 6 — Check: returning x = 0.8750 to
reproduces the given quantities, and both sides carry the same units.
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
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
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
Step 1 — State the governing relation:
Step 2 — Rearrange the relation so that y stands alone on the left-hand side.
Step 3
Step 4 — Substitute the given values into the rearranged relation.
Step 5 — Evaluate:
Step 6 — Check: returning y = 13.6000 to
reproduces the given quantities, and both sides carry the same units.
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
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
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
Step 1 — State the governing relation:
Step 2 — Rearrange the relation so that m stands alone on the left-hand side.
Step 3
Step 4 — Substitute the given values into the rearranged relation.
Step 5 — Evaluate:
Step 6 — Check: returning m = 3.6429 to
reproduces the given quantities, and both sides carry the same units.
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