(25-x)(x-7)=0

Solution for (25-x)(x-7)=0 equation:

(25-x)(x-7)=0

We add all the numbers together, and all the variables

(-1x+25)(x-7)=0

We multiply parentheses ..

(-1x^2+7x+25x-175)=0

We get rid of parentheses

-1x^2+7x+25x-175=0

We add all the numbers together, and all the variables

-1x^2+32x-175=0

a = -1; b = 32; c = -175;
Δ = b2-4ac
Δ = 322-4·(-1)·(-175)
Δ = 324
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{324}=18$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(32)-18}{2*-1}=\frac{-50}{-2}
=+25
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(32)+18}{2*-1}=\frac{-14}{-2}
=+7
$