1.8=8x-4.9x^2

Solution for 1.8=8x-4.9x^2 equation:

1.8=8x-4.9x^2

We move all terms to the left:

1.8-(8x-4.9x^2)=0

We get rid of parentheses

4.9x^2-8x+1.8=0

a = 4.9; b = -8; c = +1.8;
Δ = b2-4ac
Δ = -82-4·4.9·1.8
Δ = 28.72
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{-(-8)-\sqrt{28.72}}{2*4.9}=\frac{8-\sqrt{28.72}}{9.8}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-8)+\sqrt{28.72}}{2*4.9}=\frac{8+\sqrt{28.72}}{9.8}
$