800=x^2+34x

Solution for 800=x^2+34x equation:

800=x^2+34x

We move all terms to the left:

800-(x^2+34x)=0

We get rid of parentheses

-x^2-34x+800=0

We add all the numbers together, and all the variables

-1x^2-34x+800=0

a = -1; b = -34; c = +800;
Δ = b2-4ac
Δ = -342-4·(-1)·800
Δ = 4356
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{4356}=66$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-34)-66}{2*-1}=\frac{-32}{-2}
=+16
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-34)+66}{2*-1}=\frac{100}{-2}
=-50
$