9x^2+90x-64=0

Solution for 9x^2+90x-64=0 equation:

9x^2+90x-64=0

a = 9; b = 90; c = -64;
Δ = b2-4ac
Δ = 902-4·9·(-64)
Δ = 10404
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{10404}=102$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(90)-102}{2*9}=\frac{-192}{18}
=-10+2/3
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(90)+102}{2*9}=\frac{12}{18}
=2/3
$