Question

If $z=\frac{(3+4i)(5-7i)}{(7+5i)(4-3i)}$ then $|z|=?$

• A. 5
• B. 4
• C. 1
• D. None of these

Answer 1

Answer: (C)

1

Given, $z=\frac{(3+4i)(5-7i)}{(7+5i)(4-3i)}$

$\therefore |z|=\frac{|(3+4i)||(5-7i)|}{|(7+5i)||(4-3i)|}$
$=\frac{\sqrt{9+16}\sqrt{25+49}}{\sqrt{49+25}\sqrt{16+9}}=1$