0=x(2)-15x+36

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

0=x(2)-15x+36

We move all terms to the left:

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

We add all the numbers together, and all the variables

-(+x^2-15x+36)+0=0

We add all the numbers together, and all the variables

-(+x^2-15x+36)=0

We get rid of parentheses

-x^2+15x-36=0

We add all the numbers together, and all the variables

-1x^2+15x-36=0

a = -1; b = 15; c = -36;
Δ = b2-4ac
Δ = 152-4·(-1)·(-36)
Δ = 81
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{81}=9$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(15)-9}{2*-1}=\frac{-24}{-2}
=+12
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(15)+9}{2*-1}=\frac{-6}{-2}
=+3
$