Question
Express the following complex numbers in the standard form a + ib: $\frac{3+2\text{i}}{-2+\text{i}}$

Answer

$\frac{3+2\text{i}}{-2+\text{i}}=\frac{3+2\text{i}}{(-2+\text{i})}\times\frac{(-2-\text{i})}{-2-\text{i}}$ [Rationalising the denominator] $=\frac{3(-2-\text{i})+2\text{i}(-2-\text{i})}{(-2)^2-(\text{i}^2)} \ \big[\because \ (\text{a}+\text{ib})(\text{a}-\text{ib})=\text{a}^2+\text{b}^2\big]$ $=\frac{-6-3\text{i}-4\text{i}+2}{4+1} \ \big[\because \ -\text{i}^2=1\big]$ $=\frac{-4-7\text{i}}{5}$ $=\frac{-4}{5}-\frac{7}{5}\text{i}$ $\therefore \ \frac{3+2\text{i}}{-2+\text{i}}=\frac{-4}{5}-\frac{7}{5}\text{i}$

Need a full question paper?

Generate a complete, print-ready paper with questions like this in minutes — across 16+ boards, with answer keys.

Start Generating Free