X^2+4x=8,25

Solution for X^2+4x=8,25 equation:

X^2+4X=8.25

We move all terms to the left:

X^2+4X-(8.25)=0

We add all the numbers together, and all the variables

X^2+4X-8.25=0

a = 1; b = 4; c = -8.25;
Δ = b2-4ac
Δ = 42-4·1·(-8.25)
Δ = 49
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$X_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$X_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{49}=7$
$X_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(4)-7}{2*1}=\frac{-11}{2}
=-5+1/2
$
$X_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(4)+7}{2*1}=\frac{3}{2}
=1+1/2
$