7x^2-3=20x

Solution for 7x^2-3=20x equation:

7x^2-3=20x

We move all terms to the left:

7x^2-3-(20x)=0

a = 7; b = -20; c = -3;
Δ = b2-4ac
Δ = -202-4·7·(-3)
Δ = 484
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{484}=22$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-20)-22}{2*7}=\frac{-2}{14}
=-1/7
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-20)+22}{2*7}=\frac{42}{14}
=3
$