X(x+2)=11.25

Solution for X(x+2)=11.25 equation:

X(X+2)=11.25

We move all terms to the left:

X(X+2)-(11.25)=0

We add all the numbers together, and all the variables

X(X+2)-11.25=0

We multiply parentheses

X^2+2X-11.25=0

a = 1; b = 2; c = -11.25;
Δ = b2-4ac
Δ = 22-4·1·(-11.25)
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{-(2)-7}{2*1}=\frac{-9}{2}
=-4+1/2
$
$X_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(2)+7}{2*1}=\frac{5}{2}
=2+1/2
$