20x-4.9x^2=-45

Solution for 20x-4.9x^2=-45 equation:

20x-4.9x^2=-45

We move all terms to the left:

20x-4.9x^2-(-45)=0

We add all the numbers together, and all the variables

-4.9x^2+20x+45=0

a = -4.9; b = 20; c = +45;
Δ = b2-4ac
Δ = 202-4·(-4.9)·45
Δ = 1282
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{-(20)-\sqrt{1282}}{2*-4.9}=\frac{-20-\sqrt{1282}}{-9.8}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(20)+\sqrt{1282}}{2*-4.9}=\frac{-20+\sqrt{1282}}{-9.8}
$