3a^2-15a=198

Solution for 3a^2-15a=198 equation:

3a^2-15a=198

We move all terms to the left:

3a^2-15a-(198)=0

a = 3; b = -15; c = -198;
Δ = b2-4ac
Δ = -152-4·3·(-198)
Δ = 2601
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$a_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$a_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{2601}=51$
$a_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-15)-51}{2*3}=\frac{-36}{6}
=-6
$
$a_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-15)+51}{2*3}=\frac{66}{6}
=11
$