Question

How would I factor :
x^4-40x^2+144

Answer 1

36+4=40
36*4=144

Answer 2

I still don't understand what I do after I get the numbers 36 and 4

Answer 3

x^4 -40x^2 +144 =

x^4 - 4x^2 - 36 x^2 + 144 =

( x^2 - 4 ) * ( x^2 - 36 ) =

(x + 2)* (x - 2) * (x + 6 ) * ( x - ?)

Fill in for the question mark.

@abishop0018