Y=-4.9t^2+6t+2

Solution for Y=-4.9t^2+6t+2 equation:

=-4.9Y^2+6Y+2

We move all terms to the left:

-(-4.9Y^2+6Y+2)=0

We get rid of parentheses

4.9Y^2-6Y-2=0

a = 4.9; b = -6; c = -2;
Δ = b2-4ac
Δ = -62-4·4.9·(-2)
Δ = 75.2
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{-(-6)-\sqrt{75.2}}{2*4.9}=\frac{6-\sqrt{75.2}}{9.8}
$
$Y_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-6)+\sqrt{75.2}}{2*4.9}=\frac{6+\sqrt{75.2}}{9.8}
$