(x)=5x^2-20

Solution for (x)=5x^2-20 equation:

(x)=5x^2-20

We move all terms to the left:

(x)-(5x^2-20)=0

We get rid of parentheses

-5x^2+x+20=0

a = -5; b = 1; c = +20;
Δ = b2-4ac
Δ = 12-4·(-5)·20
Δ = 401
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(1)-\sqrt{401}}{2*-5}=\frac{-1-\sqrt{401}}{-10}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(1)+\sqrt{401}}{2*-5}=\frac{-1+\sqrt{401}}{-10}
$