9x^2-80x-100=0

Solution for 9x^2-80x-100=0 equation:

9x^2-80x-100=0

a = 9; b = -80; c = -100;
Δ = b2-4ac
Δ = -802-4·9·(-100)
Δ = 10000
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{10000}=100$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-80)-100}{2*9}=\frac{-20}{18}
=-1+1/9
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-80)+100}{2*9}=\frac{180}{18}
=10
$