Question
Find the conjugates of the following complex numbers: $\frac{(3-2\text{i})(2+3\text{i})}{(1+2\text{i})(2-\text{i})}$

Answer

Let $\text{z}=\frac{(3-2\text{i})(2+3\text{i})}{(1+2\text{i})(2-\text{i})}$ $=\frac{3(2+3\text{i})-2\text{i}(2+3\text{i})}{2-\text{i}+2\text{i}(2-\text{i})}$ $=\frac{6+9\text{i}-4\text{i}+6}{2-\text{i}+4\text{i}+2}$ $=\frac{12+5\text{i}}{4+3\text{i}}$ $=\frac{12+5\text{i}}{4+3\text{i}}\times\frac{4-3\text{i}}{4-3\text{i}}$ $=\frac{12(4-3\text{i})+5\text{i}(4-3\text{i})}{4(4-3\text{i})+3\text{i}(4-3\text{i})}$ $=\frac{48-36\text{i}+20\text{i}+15}{16-12\text{i}+12\text{i}+9}$ $=\frac{63-16\text{i}}{16+9}$ $\Rightarrow\text{z}=\frac{63-16\text{i}}{25}$ $\therefore \bar{\text{z}}=\frac{63+16\text{i}}{25}$ $=\frac{63}{25}+=\frac{16}{25}\text{i}$

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