I(x)=x2-1

Solution for I(x)=x2-1 equation:

(I)=I2-1

We move all terms to the left:

(I)-(I2-1)=0

We add all the numbers together, and all the variables

-(+I^2-1)+I=0

We get rid of parentheses

-I^2+I+1=0

We add all the numbers together, and all the variables

-1I^2+I+1=0

a = -1; b = 1; c = +1;
Δ = b2-4ac
Δ = 12-4·(-1)·1
Δ = 5
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$I_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$I_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$I_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(1)-\sqrt{5}}{2*-1}=\frac{-1-\sqrt{5}}{-2}
$
$I_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(1)+\sqrt{5}}{2*-1}=\frac{-1+\sqrt{5}}{-2}
$