0=5x^2-45x+40

Solution for 0=5x^2-45x+40 equation:

0=5x^2-45x+40

We move all terms to the left:

0-(5x^2-45x+40)=0

We add all the numbers together, and all the variables

-(5x^2-45x+40)=0

We get rid of parentheses

-5x^2+45x-40=0

a = -5; b = 45; c = -40;
Δ = b2-4ac
Δ = 452-4·(-5)·(-40)
Δ = 1225
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{1225}=35$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(45)-35}{2*-5}=\frac{-80}{-10}
=+8
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(45)+35}{2*-5}=\frac{-10}{-10}
=1
$