x2+9x=43.75

Solution for x2+9x=43.75 equation:

x2+9x=43.75

We move all terms to the left:

x2+9x-(43.75)=0

We add all the numbers together, and all the variables

x^2+9x-43.75=0

a = 1; b = 9; c = -43.75;
Δ = b2-4ac
Δ = 92-4·1·(-43.75)
Δ = 256
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{256}=16$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(9)-16}{2*1}=\frac{-25}{2}
=-12+1/2
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(9)+16}{2*1}=\frac{7}{2}
=3+1/2
$