1.25x^2+3x=216

Solution for 1.25x^2+3x=216 equation:

1.25x^2+3x=216

We move all terms to the left:

1.25x^2+3x-(216)=0

a = 1.25; b = 3; c = -216;
Δ = b2-4ac
Δ = 32-4·1.25·(-216)
Δ = 1089
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{1089}=33$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(3)-33}{2*1.25}=\frac{-36}{2.5}
=-14+1/2.5
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(3)+33}{2*1.25}=\frac{30}{2.5}
=12
$