20+-45x+-5x^2=0

Solution for 20+-45x+-5x^2=0 equation:

20+-45x+-5x^2=0

We add all the numbers together, and all the variables

-5x^2-45x=0

a = -5; b = -45; c = 0;
Δ = b2-4ac
Δ = -452-4·(-5)·0
Δ = 2025
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{2025}=45$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-45)-45}{2*-5}=\frac{0}{-10}
=0
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-45)+45}{2*-5}=\frac{90}{-10}
=-9
$