9(t)=-4.8t^2+9.8t

Solution for 9(t)=-4.8t^2+9.8t equation:

9(t)=-4.8t^2+9.8t

We move all terms to the left:

9(t)-(-4.8t^2+9.8t)=0

We get rid of parentheses

4.8t^2-9.8t+9t=0

We add all the numbers together, and all the variables

4.8t^2-0.8t=0

a = 4.8; b = -0.8; c = 0;
Δ = b2-4ac
Δ = -0.82-4·4.8·0
Δ = 0.64
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{-(-0.8)-\sqrt{0.64}}{2*4.8}=\frac{0.8-\sqrt{0.64}}{9.6}
$
$t_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-0.8)+\sqrt{0.64}}{2*4.8}=\frac{0.8+\sqrt{0.64}}{9.6}
$