Y=3-4.9t^2

Solution for Y=3-4.9t^2 equation:

=3-4.9Y^2

We move all terms to the left:

-(3-4.9Y^2)=0

We get rid of parentheses

4.9Y^2-3=0

a = 4.9; b = 0; c = -3;
Δ = b2-4ac
Δ = 02-4·4.9·(-3)
Δ = 58.8
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{-(0)-\sqrt{58.8}}{2*4.9}=\frac{0-\sqrt{58.8}}{9.8}
=-\frac{\sqrt{}}{9.8}
$
$Y_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(0)+\sqrt{58.8}}{2*4.9}=\frac{0+\sqrt{58.8}}{9.8}
=\frac{\sqrt{}}{9.8}
$