4x^2-56x+135=0

Solution for 4x^2-56x+135=0 equation:

4x^2-56x+135=0

a = 4; b = -56; c = +135;
Δ = b2-4ac
Δ = -562-4·4·135
Δ = 976
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:

$\sqrt{\Delta}=\sqrt{976}=\sqrt{16*61}=\sqrt{16}*\sqrt{61}=4\sqrt{61}$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-56)-4\sqrt{61}}{2*4}=\frac{56-4\sqrt{61}}{8}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-56)+4\sqrt{61}}{2*4}=\frac{56+4\sqrt{61}}{8}
$