Solve for f.

(f - 12)2 = 25

A. f = 5 or f = −5

B. f = 12 or f = −12

C. f = 17 or f = 7

D. no solution

2 answers

Multiply to get rid of the parenthesis.

2f - 24 = 25

Add 24 to both sides.

2f = 49

Divide both sides by 2.

f = 28.5

Unless you have a typo somewhere, none of the alternatives fit.
Looks like he meant

(f-12)^2 = 25
so,
f-12 = ±5
f = 12±5
f = 17 or 7