Question

Could someone show me why I got this problem wrong?

Answer 1

The problem is: \[x^4 - 2x^2 - 8\]

I originally got: (x - 4)(x + 2)

Now I have: (x - 2)(x + 2). Would this be correct?

Answer 2

lets, just for simplification, put x^2 =y

so, x^4 = y^2
right ?

Answer 3

Yes.

Answer 4

so the equation now is
y^2-2y-8

can u factor this ?

Answer 5

I realize that's why I got it wrong the first time.

Answer 6

(x - 4)(x + 2)

Answer 7

you mean (y-4)(y+2)
isn't it ?

Answer 8

Which would then turn into (x - 2)(x + 2). Also, the original problem had x not y.

Answer 9

we put x^2 as 'y' remember ?

so, wouldn't that be
(x^2-4)(x^2+2)
now ?

Answer 10

Oh yes! I had simplified that into (x - 2)(x + 2).

Answer 11

x^2-4 is indeed (x - 2)(x + 2)

so finally it would be
(x - 2)(x + 2)(x^2+2)
got it ?

Answer 12

I understand now, thank you.

Answer 13

welcome ^_^