x^2+28x+135=0

Solution for x^2+28x+135=0 equation:

x^2+28x+135=0

a = 1; b = 28; c = +135;
Δ = b2-4ac
Δ = 282-4·1·135
Δ = 244
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:

$\sqrt{\Delta}=\sqrt{244}=\sqrt{4*61}=\sqrt{4}*\sqrt{61}=2\sqrt{61}$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(28)-2\sqrt{61}}{2*1}=\frac{-28-2\sqrt{61}}{2}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(28)+2\sqrt{61}}{2*1}=\frac{-28+2\sqrt{61}}{2}
$