-28x^2+84x+1120=0

Solution for -28x^2+84x+1120=0 equation:

-28x^2+84x+1120=0

a = -28; b = 84; c = +1120;
Δ = b2-4ac
Δ = 842-4·(-28)·1120
Δ = 132496
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{132496}=364$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(84)-364}{2*-28}=\frac{-448}{-56}
=+8
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(84)+364}{2*-28}=\frac{280}{-56}
=-5
$