Question

How would you solve x^4=2x^2 - 1?

Answer 1

still not understanding..

Answer 2

rewrite it as \[x^4 - 2x^2 + 1 = 0\]

let

\[u = x^2\]

solve u^2 -2u+ 1 = 0

which is (u - 1)^2 = 0

then u = 1 is a solution but since u = x^2 then x^2 = 1 or

\[x = \pm\]

Answer 3

oops \[x = \pm 1\]

Answer 4

where'd u come from is what I'm curious of?

Answer 5

IT MAKES SENSE NOW!!! THANKYOU