x2+20x+72=3x

Solution for x2+20x+72=3x equation:

x2+20x+72=3x

We move all terms to the left:

x2+20x+72-(3x)=0

We add all the numbers together, and all the variables

x^2+17x+72=0

a = 1; b = 17; c = +72;
Δ = b2-4ac
Δ = 172-4·1·72
Δ = 1
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{1}=1$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(17)-1}{2*1}=\frac{-18}{2}
=-9
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(17)+1}{2*1}=\frac{-16}{2}
=-8
$