3.9.2—Complex numbers
- Syllabus
- 9709–2028–2029
- Objective
- 3.9.2
- Level
- A2
Complex arithmetic is checked by matching real and imaginary parts
Add complex numbers componentwise, multiply by expanding and replace i² with −1, and divide by multiplying numerator and denominator by the denominator’s conjugate.
After simplifying, write the answer in a+bi form. Equality of complex numbers requires equality of both components.
(1+2i)/(3−i) =[(1+2i)(3+i)]/10=(1+7i)/10.
A complex fraction is not simplified by dividing real parts and imaginary parts separately.
ConceptA-Level CAIE Mathematics A2