3x^2+15x-7.9=0

Solution for 3x^2+15x-7.9=0 equation:

3x^2+15x-7.9=0

a = 3; b = 15; c = -7.9;
Δ = b2-4ac
Δ = 152-4·3·(-7.9)
Δ = 319.8
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(15)-\sqrt{319.8}}{2*3}=\frac{-15-\sqrt{319.8}}{6}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(15)+\sqrt{319.8}}{2*3}=\frac{-15+\sqrt{319.8}}{6}
$