-0.1x^2+2.2x-7.2=0

Solution for -0.1x^2+2.2x-7.2=0 equation:

-0.1x^2+2.2x-7.2=0

a = -0.1; b = 2.2; c = -7.2;
Δ = b2-4ac
Δ = 2.22-4·(-0.1)·(-7.2)
Δ = 1.96
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{-(2.2)-\sqrt{1.96}}{2*-0.1}=\frac{-2.2-\sqrt{1.96}}{-0.2}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(2.2)+\sqrt{1.96}}{2*-0.1}=\frac{-2.2+\sqrt{1.96}}{-0.2}
$