-1.8=2.25x-4.9x^2

Solution for -1.8=2.25x-4.9x^2 equation:

-1.8=2.25x-4.9x^2

We move all terms to the left:

-1.8-(2.25x-4.9x^2)=0

We get rid of parentheses

4.9x^2-2.25x-1.8=0

a = 4.9; b = -2.25; c = -1.8;
Δ = b2-4ac
Δ = -2.252-4·4.9·(-1.8)
Δ = 40.3425
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{-(-2.25)-\sqrt{40.3425}}{2*4.9}=\frac{2.25-\sqrt{40.3425}}{9.8}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-2.25)+\sqrt{40.3425}}{2*4.9}=\frac{2.25+\sqrt{40.3425}}{9.8}
$