3x^2+27x-7.5=0

Solution for 3x^2+27x-7.5=0 equation:

3x^2+27x-7.5=0

a = 3; b = 27; c = -7.5;
Δ = b2-4ac
Δ = 272-4·3·(-7.5)
Δ = 819
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:

$\sqrt{\Delta}=\sqrt{819}=\sqrt{9*91}=\sqrt{9}*\sqrt{91}=3\sqrt{91}$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(27)-3\sqrt{91}}{2*3}=\frac{-27-3\sqrt{91}}{6}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(27)+3\sqrt{91}}{2*3}=\frac{-27+3\sqrt{91}}{6}
$