X^2+6.5x=20

Solution for X^2+6.5x=20 equation:

X^2+6.5X=20

We move all terms to the left:

X^2+6.5X-(20)=0

a = 1; b = 6.5; c = -20;
Δ = b2-4ac
Δ = 6.52-4·1·(-20)
Δ = 122.25
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$X_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$X_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$X_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(6.5)-\sqrt{122.25}}{2*1}=\frac{-6.5-\sqrt{122.25}}{2}
$
$X_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(6.5)+\sqrt{122.25}}{2*1}=\frac{-6.5+\sqrt{122.25}}{2}
$