5x^2+18x-15=0

Solution for 5x^2+18x-15=0 equation:

5x^2+18x-15=0

a = 5; b = 18; c = -15;
Δ = b2-4ac
Δ = 182-4·5·(-15)
Δ = 624
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:

$\sqrt{\Delta}=\sqrt{624}=\sqrt{16*39}=\sqrt{16}*\sqrt{39}=4\sqrt{39}$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(18)-4\sqrt{39}}{2*5}=\frac{-18-4\sqrt{39}}{10}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(18)+4\sqrt{39}}{2*5}=\frac{-18+4\sqrt{39}}{10}
$