Answer:
A
Step-by-step explanation:
Noting that i² = - 1
Given
(7 - 3i)(8 + 4i) ← expand factors using FOIL
= 56 + 28i - 24i - 12i²
= 56 + 4i - 12(- 1)
= 56 + 4i + 12
= 68 + 4i → A
Answer:

Step-by-step explanation:
The arcs LY, KM, KL and MJ together form the full revolution angle, thus

Note that

then

So,

Also

so

In triangle EML,

Thus, 
Check the picture below.
make sure your calculator is in Degree mode.
It's choice C as the root overhead bar goes over all of (x-7) and not just the x. So you have the correct answer.
f(x) = x^4+7
y = x^4+7
x = y^4+7
y^4 = x-7
y = FourthRoot(x-7)