x^2+x^2-4x=165

Solution for x^2+x^2-4x=165 equation:

x^2+x^2-4x=165

We move all terms to the left:

x^2+x^2-4x-(165)=0

We add all the numbers together, and all the variables

2x^2-4x-165=0

a = 2; b = -4; c = -165;
Δ = b2-4ac
Δ = -42-4·2·(-165)
Δ = 1336
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:

$\sqrt{\Delta}=\sqrt{1336}=\sqrt{4*334}=\sqrt{4}*\sqrt{334}=2\sqrt{334}$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-4)-2\sqrt{334}}{2*2}=\frac{4-2\sqrt{334}}{4}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-4)+2\sqrt{334}}{2*2}=\frac{4+2\sqrt{334}}{4}
$