30-12x=4.9x^2

Solution for 30-12x=4.9x^2 equation:

30-12x=4.9x^2

We move all terms to the left:

30-12x-(4.9x^2)=0

We get rid of parentheses

-4.9x^2-12x+30=0

a = -4.9; b = -12; c = +30;
Δ = b2-4ac
Δ = -122-4·(-4.9)·30
Δ = 732
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

The end solution:

$\sqrt{\Delta}=\sqrt{732}=\sqrt{4*183}=\sqrt{4}*\sqrt{183}=2\sqrt{183}$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-12)-2\sqrt{183}}{2*-4.9}=\frac{12-2\sqrt{183}}{-9.8}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-12)+2\sqrt{183}}{2*-4.9}=\frac{12+2\sqrt{183}}{-9.8}
$