3. 7x^2 – 144 = –x^4 (1 point)

please help, & walk thru...

Question

3.   7x^2 – 144 = –x^4  (1 point)

please help, & walk thru...

anonymous · Answer

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

anonymous · Answer

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

anonymous · Answer

$$7x^2 - 144 = -x^4$$
$$x^4 + 7x^2 - 144 = 0$$ 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

anonymous · Answer

so I added x^4 to each side?

anonymous · Answer

Yes

anonymous · Answer

And Im confused on what to do after that?

anonymous · Answer

so then do i add 144 to each side?

anonymous · Answer

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

anonymous · Answer

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

anonymous · Answer

Thank u :-) Got it right!