2x^2-0.3x=9

Solution for 2x^2-0.3x=9 equation:

2x^2-0.3x=9

We move all terms to the left:

2x^2-0.3x-(9)=0

a = 2; b = -0.3; c = -9;
Δ = b2-4ac
Δ = -0.32-4·2·(-9)
Δ = 72.09
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{-(-0.3)-\sqrt{72.09}}{2*2}=\frac{0.3-\sqrt{72.09}}{4}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-0.3)+\sqrt{72.09}}{2*2}=\frac{0.3+\sqrt{72.09}}{4}
$