11x^2-20x-28=0

Solution for 11x^2-20x-28=0 equation:

11x^2-20x-28=0

a = 11; b = -20; c = -28;
Δ = b2-4ac
Δ = -202-4·11·(-28)
Δ = 1632
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:

$\sqrt{\Delta}=\sqrt{1632}=\sqrt{16*102}=\sqrt{16}*\sqrt{102}=4\sqrt{102}$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-20)-4\sqrt{102}}{2*11}=\frac{20-4\sqrt{102}}{22}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-20)+4\sqrt{102}}{2*11}=\frac{20+4\sqrt{102}}{22}
$