Question

16. (9 - 61)(4 - 21)36 -24ib. 24 + 42i24 - 42i

Answer 1

$(9-6i)(4-2i)$

We will start with multiplying 9 by 4

$9\times4=36$

Then multiply 9 by -2i

$9\times-2i=-18i$

then multiply -6i by 4

$-6i\times4=-24i$

Then multiply -6i by -2i

$-6i\times-2i=12i^2$

The value of i^2 is -1, then multiply 12 by -1

$-6i\times-2i=12i^2=12\times-1=-12$

Now, we will collect them together

$36-18i-24i-12$

We will add the like terms

$(36-12)+(-18i-24i)=24+(-42i)=24-42i$

The answer is c