12=-4.9x^2+8x+12

Solution for 12=-4.9x^2+8x+12 equation:

12=-4.9x^2+8x+12

We move all terms to the left:

12-(-4.9x^2+8x+12)=0

We get rid of parentheses

4.9x^2-8x-12+12=0

We add all the numbers together, and all the variables

4.9x^2-8x=0

a = 4.9; b = -8; c = 0;
Δ = b2-4ac
Δ = -82-4·4.9·0
Δ = 64
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{64}=8$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-8)-8}{2*4.9}=\frac{0}{9.8}
=0
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-8)+8}{2*4.9}=\frac{16}{9.8}
=1+1.9375/3.0625
$