30-x=40x2

Solution for 30-x=40x2 equation:

30-x=40x^2

We move all terms to the left:

30-x-(40x^2)=0

determiningTheFunctionDomain
-40x^2-x+30=0

We add all the numbers together, and all the variables

-40x^2-1x+30=0

a = -40; b = -1; c = +30;
Δ = b2-4ac
Δ = -12-4·(-40)·30
Δ = 4801
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{4801}}{2*-40}=\frac{1-\sqrt{4801}}{-80}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-1)+\sqrt{4801}}{2*-40}=\frac{1+\sqrt{4801}}{-80}
$