3x2+18=15x

Solution for 3x2+18=15x equation:

3x^2+18=15x

We move all terms to the left:

3x^2+18-(15x)=0

a = 3; b = -15; c = +18;
Δ = b2-4ac
Δ = -152-4·3·18
Δ = 9
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{9}=3$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-15)-3}{2*3}=\frac{12}{6}
=2
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-15)+3}{2*3}=\frac{18}{6}
=3
$