x^2+x=8,75

Solution for x^2+x=8,75 equation:

x^2+x=8.75

We move all terms to the left:

x^2+x-(8.75)=0

We add all the numbers together, and all the variables

x^2+x-8.75=0

a = 1; b = 1; c = -8.75;
Δ = b2-4ac
Δ = 12-4·1·(-8.75)
Δ = 36
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{36}=6$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(1)-6}{2*1}=\frac{-7}{2}
=-3+1/2
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(1)+6}{2*1}=\frac{5}{2}
=2+1/2
$