x2+100x=3900

Solution for x2+100x=3900 equation:

X2+100X=3900

We move all terms to the left:

X2+100X-(3900)=0

We add all the numbers together, and all the variables

X^2+100X-3900=0

a = 1; b = 100; c = -3900;
Δ = b2-4ac
Δ = 1002-4·1·(-3900)
Δ = 25600
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$X_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$X_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{25600}=160$
$X_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(100)-160}{2*1}=\frac{-260}{2}
=-130
$
$X_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(100)+160}{2*1}=\frac{60}{2}
=30
$