Help with these equations

Question

Perform the indicated operation. Write answers in the form a+bi 

 

(7+i) - (3-4i)

 

(4-i)(3+7i)

Answer 1

These are NOT eequations; they're expressions in which you are asked to simplify. 

The first one will be 7 - 3 + i + 4i = 4 + 5i

 

The second one requires FOILing and also remembering that i squared becomes -1:

= 12 +28i - 3i -7i²

=12 + 7 + 25i = 19 + 25i...[note rearrangement of last term above & its interpretation as + 7]