2.0=15t-4.905t2

Solution for 2.0=15t-4.905t2 equation:

2.0=15t-4.905t^2

We move all terms to the left:

2.0-(15t-4.905t^2)=0

We add all the numbers together, and all the variables

-(15t-4.905t^2)+2=0

We get rid of parentheses

4.905t^2-15t+2=0

a = 4.905; b = -15; c = +2;
Δ = b2-4ac
Δ = -152-4·4.905·2
Δ = 185.76
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$t_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$t_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$t_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-15)-\sqrt{185.76}}{2*4.905}=\frac{15-\sqrt{185.76}}{9.81}
$
$t_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-15)+\sqrt{185.76}}{2*4.905}=\frac{15+\sqrt{185.76}}{9.81}
$