5x^2-10x-330=15

Solution for 5x^2-10x-330=15 equation:

5x^2-10x-330=15

We move all terms to the left:

5x^2-10x-330-(15)=0

We add all the numbers together, and all the variables

5x^2-10x-345=0

a = 5; b = -10; c = -345;
Δ = b2-4ac
Δ = -102-4·5·(-345)
Δ = 7000
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:

$\sqrt{\Delta}=\sqrt{7000}=\sqrt{100*70}=\sqrt{100}*\sqrt{70}=10\sqrt{70}$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-10)-10\sqrt{70}}{2*5}=\frac{10-10\sqrt{70}}{10}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-10)+10\sqrt{70}}{2*5}=\frac{10+10\sqrt{70}}{10}
$