1. ## using quadratic formula to find irrational roots

given x^4-5x^2+4...how can i use the quadratic formula to find irrational roots? i know that i need to transform x^4...but i don't know how...
thanks

2. Originally Posted by alessandromangione
given x^4-5x^2+4...how can i use the quadratic formula to find irrational roots? i know that i need to transform x^4...but i don't know how...
thanks
$x^4-5x^2+4=0$

Let $y=x^2$

So $y^2-5y+4=0$

Solve for $y$, then go back and find $x$.