25x-75+3x+9-2x^2+18=0

Solution for 25x-75+3x+9-2x^2+18=0 equation:

25x-75+3x+9-2x^2+18=0

We add all the numbers together, and all the variables

-2x^2+28x-48=0

a = -2; b = 28; c = -48;
Δ = b2-4ac
Δ = 282-4·(-2)·(-48)
Δ = 400
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{400}=20$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(28)-20}{2*-2}=\frac{-48}{-4}
=+12
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(28)+20}{2*-2}=\frac{-8}{-4}
=+2
$