5x^2+10x-165=0

Solution for 5x^2+10x-165=0 equation:

5x^2+10x-165=0

a = 5; b = 10; c = -165;
Δ = b2-4ac
Δ = 102-4·5·(-165)
Δ = 3400
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:

$\sqrt{\Delta}=\sqrt{3400}=\sqrt{100*34}=\sqrt{100}*\sqrt{34}=10\sqrt{34}$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(10)-10\sqrt{34}}{2*5}=\frac{-10-10\sqrt{34}}{10}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(10)+10\sqrt{34}}{2*5}=\frac{-10+10\sqrt{34}}{10}
$