(4x^2+56x-20)=0

Solution for (4x^2+56x-20)=0 equation:

(4x^2+56x-20)=0

We get rid of parentheses

4x^2+56x-20=0

a = 4; b = 56; c = -20;
Δ = b2-4ac
Δ = 562-4·4·(-20)
Δ = 3456
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:

$\sqrt{\Delta}=\sqrt{3456}=\sqrt{576*6}=\sqrt{576}*\sqrt{6}=24\sqrt{6}$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(56)-24\sqrt{6}}{2*4}=\frac{-56-24\sqrt{6}}{8}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(56)+24\sqrt{6}}{2*4}=\frac{-56+24\sqrt{6}}{8}
$