Question

3. 7x^2 – 144 = –x^4 (1 point)

please help, & walk thru...

Answer 1

3, –3, 4i, 0
3, 4i
3, –3, 4i, –4i
–3, –4i

Answer 2

those are the answer choices, but i'd like to learn how to solve this too.

Answer 3

\[7x^2 - 144 = -x^4\]
\[x^4 + 7x^2 - 144 = 0\] let p = x^2, then:
\[p^2 + 7p - 144 = 0\]
This is just a quadratic equation which you can solve for p, and then use p = x^2 to find out what x can be

Answer 4

so I added x^4 to each side?

Answer 5

Yes

Answer 6

And Im confused on what to do after that?

Answer 7

so then do i add 144 to each side?

Answer 8

No, you let p = x^2 and substitute that into the original equation.
Then you get a quadratic equation you can solve by using the quadratic formula

Answer 9

Ohhh so it's C? 3,-3, 4i, -4i?

Answer 10

Thank u :-) Got it right!