Let a=x^2+4. use a to find the solutions for the following equation:
(x^2+4)^2+32=12x^2+48
which of the following are solutions for x?
a.-8
b.-2
c.4
d. 0
e.2
f.-4
g.8

(x^2+4)^2 + 32 = 12x^2 + 48 a = x^2 + 4 
(x^2 + 4)^2 + 32 = 12(x^2 + 4) 
a^2 + 32 = 12a 
a^2 - 12a + 32 = 0 
(a - 8)(a - 4) = 0 
a = 8 and a = 4 

for a = 8 ... 8 = x^2 + 4 ... x^2 = 4 ... x = +/- 2 
for a = 4 ... 4 = x^2 + 4 ... x^2 = 0 ... x = 0 

x = -2, 0, +2 so your answer is going to be e


Here are the answers to the ones that i could see.