X2+3.4x=11.56

Solution for X2+3.4x=11.56 equation:

X2+3.4X=11.56

We move all terms to the left:

X2+3.4X-(11.56)=0

We add all the numbers together, and all the variables

X^2+3.4X-11.56=0

a = 1; b = 3.4; c = -11.56;
Δ = b2-4ac
Δ = 3.42-4·1·(-11.56)
Δ = 57.8
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$X_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$X_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$X_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(3.4)-\sqrt{57.8}}{2*1}=\frac{-3.4-\sqrt{57.8}}{2}
$
$X_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(3.4)+\sqrt{57.8}}{2*1}=\frac{-3.4+\sqrt{57.8}}{2}
$