X^2+x=1.21

Solution for X^2+x=1.21 equation:

X^2+X=1.21

We move all terms to the left:

X^2+X-(1.21)=0

We add all the numbers together, and all the variables

X^2+X-1.21=0

a = 1; b = 1; c = -1.21;
Δ = b2-4ac
Δ = 12-4·1·(-1.21)
Δ = 5.84
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{-(1)-\sqrt{5.84}}{2*1}=\frac{-1-\sqrt{5.84}}{2}
$
$X_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(1)+\sqrt{5.84}}{2*1}=\frac{-1+\sqrt{5.84}}{2}
$