Question

Two complex numbers are represented by ordered pairs $z_1:(2,4)\&z_2:(-4,5)$, which of the following is real part for $z_1\times z_2=$?

• A. $-6$
• B. $-28$
• C. $6$
• D. None of these

Answer 1

Answer: (B)

$-28$

$z_1$ : (2,4) = 2 + 4i

$z_2$ : (-4,5) = -4 + 5i

$\therefore$ $z_1\times z_2$ = (2+4i)(-4+5i)

= -28 - 6i

$\Rightarrow$ Real part ( $z_1\times z_2$ ) = -28

Hence, option B is correct.