x2+1.65x-7.84=0

Solution for x2+1.65x-7.84=0 equation:

x2+1.65x-7.84=0

We add all the numbers together, and all the variables

x^2+1.65x-7.84=0

a = 1; b = 1.65; c = -7.84;
Δ = b2-4ac
Δ = 1.652-4·1·(-7.84)
Δ = 34.0825
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{-(1.65)-\sqrt{34.0825}}{2*1}=\frac{-1.65-\sqrt{34.0825}}{2}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(1.65)+\sqrt{34.0825}}{2*1}=\frac{-1.65+\sqrt{34.0825}}{2}
$