X^2+1.3x=1.69

Solution for X^2+1.3x=1.69 equation:

X^2+1.3X=1.69

We move all terms to the left:

X^2+1.3X-(1.69)=0

We add all the numbers together, and all the variables

X^2+1.3X-1.69=0

a = 1; b = 1.3; c = -1.69;
Δ = b2-4ac
Δ = 1.32-4·1·(-1.69)
Δ = 8.45
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{-(1.3)-\sqrt{8.45}}{2*1}=\frac{-1.3-\sqrt{8.45}}{2}
$
$X_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(1.3)+\sqrt{8.45}}{2*1}=\frac{-1.3+\sqrt{8.45}}{2}
$