3c^2-8c-15=-4

Solution for 3c^2-8c-15=-4 equation:

3c^2-8c-15=-4

We move all terms to the left:

3c^2-8c-15-(-4)=0

We add all the numbers together, and all the variables

3c^2-8c-11=0

a = 3; b = -8; c = -11;
Δ = b2-4ac
Δ = -82-4·3·(-11)
Δ = 196
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$c_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$c_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{196}=14$
$c_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-8)-14}{2*3}=\frac{-6}{6}
=-1
$
$c_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-8)+14}{2*3}=\frac{22}{6}
=3+2/3
$