-9x^2+56x+90=0

Solution for -9x^2+56x+90=0 equation:

-9x^2+56x+90=0

a = -9; b = 56; c = +90;
Δ = b2-4ac
Δ = 562-4·(-9)·90
Δ = 6376
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:

$\sqrt{\Delta}=\sqrt{6376}=\sqrt{4*1594}=\sqrt{4}*\sqrt{1594}=2\sqrt{1594}$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(56)-2\sqrt{1594}}{2*-9}=\frac{-56-2\sqrt{1594}}{-18}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(56)+2\sqrt{1594}}{2*-9}=\frac{-56+2\sqrt{1594}}{-18}
$