-3x^2-13x+56=0

Solution for -3x^2-13x+56=0 equation:

-3x^2-13x+56=0

a = -3; b = -13; c = +56;
Δ = b2-4ac
Δ = -132-4·(-3)·56
Δ = 841
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{841}=29$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-13)-29}{2*-3}=\frac{-16}{-6}
=2+2/3
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-13)+29}{2*-3}=\frac{42}{-6}
=-7
$