Question

Your friend multiplied complex numbers and expressions as shown. Find the error in your friends work. Then factor the expression correctly. Show work please.

(4-7i)(4+7i)=16+28i-28i+49i^2
=16-49
=-33

Answer 1

= 16+49 = 65

Explanation:

The error is at the end of the first line. (-7i)(7i) = -49i² ≠ +49i².

The correct work is ...

(4-7i)(4+7i)=16+28i-28i-49i^2

= 16+49

= 65