0=5x^2-40x+70

Solution for 0=5x^2-40x+70 equation:

0=5x^2-40x+70

We move all terms to the left:

0-(5x^2-40x+70)=0

We add all the numbers together, and all the variables

-(5x^2-40x+70)=0

We get rid of parentheses

-5x^2+40x-70=0

a = -5; b = 40; c = -70;
Δ = b2-4ac
Δ = 402-4·(-5)·(-70)
Δ = 200
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

The end solution:

$\sqrt{\Delta}=\sqrt{200}=\sqrt{100*2}=\sqrt{100}*\sqrt{2}=10\sqrt{2}$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(40)-10\sqrt{2}}{2*-5}=\frac{-40-10\sqrt{2}}{-10}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(40)+10\sqrt{2}}{2*-5}=\frac{-40+10\sqrt{2}}{-10}
$