D) 36x^2-81
both 36x^2 and -81 are perfect squares
difference means subtraction
1.

2.
<u> </u><u>Sub (1, -5) into equation to find '</u><em><u>b'</u></em><u />
3.

4.
How to get answer by Mimiwhatsup (In Decimal Form):

Answer in Fraction Form: 
Answer: x=4
Step-by-step explanation:
-8-x=x-4x
-8-x=-3x
-8=-2x
x=4