(9-x)*(x+17)=0

Solution for (9-x)*(x+17)=0 equation:

(9-x)(x+17)=0

We add all the numbers together, and all the variables

(-1x+9)(x+17)=0

We multiply parentheses ..

(-1x^2-17x+9x+153)=0

We get rid of parentheses

-1x^2-17x+9x+153=0

We add all the numbers together, and all the variables

-1x^2-8x+153=0

a = -1; b = -8; c = +153;
Δ = b2-4ac
Δ = -82-4·(-1)·153
Δ = 676
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{676}=26$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-8)-26}{2*-1}=\frac{-18}{-2}
=+9
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-8)+26}{2*-1}=\frac{34}{-2}
=-17
$