3x^2+8x-15=0

Solution for 3x^2+8x-15=0 equation:

3x^2+8x-15=0

a = 3; b = 8; c = -15;
Δ = b2-4ac
Δ = 82-4·3·(-15)
Δ = 244
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:

$\sqrt{\Delta}=\sqrt{244}=\sqrt{4*61}=\sqrt{4}*\sqrt{61}=2\sqrt{61}$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(8)-2\sqrt{61}}{2*3}=\frac{-8-2\sqrt{61}}{6}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(8)+2\sqrt{61}}{2*3}=\frac{-8+2\sqrt{61}}{6}
$