9x^2-64x-320=0

Solution for 9x^2-64x-320=0 equation:

9x^2-64x-320=0

a = 9; b = -64; c = -320;
Δ = b2-4ac
Δ = -642-4·9·(-320)
Δ = 15616
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:

$\sqrt{\Delta}=\sqrt{15616}=\sqrt{256*61}=\sqrt{256}*\sqrt{61}=16\sqrt{61}$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-64)-16\sqrt{61}}{2*9}=\frac{64-16\sqrt{61}}{18}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-64)+16\sqrt{61}}{2*9}=\frac{64+16\sqrt{61}}{18}
$