9x^2-100x-20=0

Solution for 9x^2-100x-20=0 equation:

9x^2-100x-20=0

a = 9; b = -100; c = -20;
Δ = b2-4ac
Δ = -1002-4·9·(-20)
Δ = 10720
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:

$\sqrt{\Delta}=\sqrt{10720}=\sqrt{16*670}=\sqrt{16}*\sqrt{670}=4\sqrt{670}$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-100)-4\sqrt{670}}{2*9}=\frac{100-4\sqrt{670}}{18}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-100)+4\sqrt{670}}{2*9}=\frac{100+4\sqrt{670}}{18}
$