3x^2+15=18x

Solution for 3x^2+15=18x equation:

3x^2+15=18x

We move all terms to the left:

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

a = 3; b = -18; c = +15;
Δ = b2-4ac
Δ = -182-4·3·15
Δ = 144
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{144}=12$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-18)-12}{2*3}=\frac{6}{6}
=1
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-18)+12}{2*3}=\frac{30}{6}
=5
$