7x^2-14=20x

Solution for 7x^2-14=20x equation:

7x^2-14=20x

We move all terms to the left:

7x^2-14-(20x)=0

a = 7; b = -20; c = -14;
Δ = b2-4ac
Δ = -202-4·7·(-14)
Δ = 792
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

The end solution:

$\sqrt{\Delta}=\sqrt{792}=\sqrt{36*22}=\sqrt{36}*\sqrt{22}=6\sqrt{22}$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-20)-6\sqrt{22}}{2*7}=\frac{20-6\sqrt{22}}{14}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-20)+6\sqrt{22}}{2*7}=\frac{20+6\sqrt{22}}{14}
$