Y=-4.9x^2+15x-9

Solution for Y=-4.9x^2+15x-9 equation:

=-4.9Y^2+15Y-9

We move all terms to the left:

-(-4.9Y^2+15Y-9)=0

We get rid of parentheses

4.9Y^2-15Y+9=0

a = 4.9; b = -15; c = +9;
Δ = b2-4ac
Δ = -152-4·4.9·9
Δ = 48.6
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$Y_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$Y_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$Y_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-15)-\sqrt{48.6}}{2*4.9}=\frac{15-\sqrt{48.6}}{9.8}
$
$Y_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-15)+\sqrt{48.6}}{2*4.9}=\frac{15+\sqrt{48.6}}{9.8}
$