Originally Posted by

**freswood** I'm quite confused by the function y = |x^2 - 1|

I understand that y = x^2 - 1 when x^2 - 1 > 0 etc

But how do you solve it?

You get x^2 - 1 > 0

x^2 > 1

x > + or - 1

but it should be x<-1 and x>1

Is there some sort of inequation sign change when one of the sides is square rooted? Thanks in advance

hello,

I start here:

x^2-1 > 0. Factorize

(x+1)(x-1) > 0. > 0 means the product is positive. A product of 2 factors is positive if the factors have equal signs: (+) * (+) > 0 or (-) * (-) > 0. "+" means greater as zero, "-" means smaller as zero.

So your inequality becomes:

Code:

x+1 > 0 and x-1 > 0 or x+1 < 0 and x+1 < 0
x > -1 and x > 1 or x < -1 and x < -1
x > 1 or x < -1

This method only works if you can factorize the term.

tschüss

EB