-1=0.3x^2-x-8

Solution for -1=0.3x^2-x-8 equation:

-1=0.3x^2-x-8

We move all terms to the left:

-1-(0.3x^2-x-8)=0

We get rid of parentheses

-0.3x^2+x+8-1=0

We add all the numbers together, and all the variables

-0.3x^2+x+7=0

a = -0.3; b = 1; c = +7;
Δ = b2-4ac
Δ = 12-4·(-0.3)·7
Δ = 9.4
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)-\sqrt{9.4}}{2*-0.3}=\frac{-1-\sqrt{9.4}}{-0.6}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(1)+\sqrt{9.4}}{2*-0.3}=\frac{-1+\sqrt{9.4}}{-0.6}
$