Question

How do you solve the equation `abs(x^2-1)=3`?

Answer 1

If this is a quadratic equation then `x=-2 or x=2`

Explanation:

`x^2-1=3`

`x^2-1-3=3-3`

`x^2-4=0`

This is a quadratic equation, in which ax^2+bx+c=0.

To solve for x the equation is `x_{1,\:2}=\frac{-b\pm \sqrt{b^2-4ac}}{2a}`

So `x=\frac{-0+\sqrt{0^2-4\cdot \1\(-4\)}}{2\cdot \1}:\quad 2`

And `x=\frac{-0-\sqrt{0^2-4\cdot \1\(-4\)}}{2\cdot \1}:\quad -2`

So `x=-2 or 2`

The dot means multiplication.