2x(14x-13)=20

Solution for 2x(14x-13)=20 equation:

2x(14x-13)=20

We move all terms to the left:

2x(14x-13)-(20)=0

We multiply parentheses

28x^2-26x-20=0

a = 28; b = -26; c = -20;
Δ = b2-4ac
Δ = -262-4·28·(-20)
Δ = 2916
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{2916}=54$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-26)-54}{2*28}=\frac{-28}{56}
=-1/2
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-26)+54}{2*28}=\frac{80}{56}
=1+3/7
$