x^2=0.3x+28x

Solution for x^2=0.3x+28x equation:

x^2=0.3x+28x

We move all terms to the left:

x^2-(0.3x+28x)=0

We add all the numbers together, and all the variables

x^2-(+28.3x)=0

We get rid of parentheses

x^2-28.3x=0

a = 1; b = -28.3; c = 0;
Δ = b2-4ac
Δ = -28.32-4·1·0
Δ = 800.89
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{-(-28.3)-\sqrt{800.89}}{2*1}=\frac{28.3-\sqrt{800.89}}{2}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-28.3)+\sqrt{800.89}}{2*1}=\frac{28.3+\sqrt{800.89}}{2}
$