9x(2)-15x-36=0

Solution for 9x(2)-15x-36=0 equation:

9x(2)-15x-36=0

We add all the numbers together, and all the variables

9x^2-15x-36=0

a = 9; b = -15; c = -36;
Δ = b2-4ac
Δ = -152-4·9·(-36)
Δ = 1521
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{1521}=39$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-15)-39}{2*9}=\frac{-24}{18}
=-1+1/3
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-15)+39}{2*9}=\frac{54}{18}
=3
$