Question

Which of the following complexe numbers is equal to (4 + 3i)(5 - 2i)?

20 + i

20+6i

26 + i^2

26 + 7i

Answer 1

I believe the answer is (d) 26 + 7i.

Answer 2

The product of (4 + 3i)(5 - 2i) can be calculated using the distributive property:

(4 + 3i)(5 - 2i) = 4 × 5 + 4 × -2i + 3i × 5 + 3i × -2i

= 20 - 8i + 15i - 6i^2

= 20 + 7i - 6(-1)

= 26 + 7i

So the answer is (4) 26 + 7i.