8=-4.9t^2+14t+2.5

Solution for 8=-4.9t^2+14t+2.5 equation:

8=-4.9t^2+14t+2.5

We move all terms to the left:

8-(-4.9t^2+14t+2.5)=0

We get rid of parentheses

4.9t^2-14t-2.5+8=0

We add all the numbers together, and all the variables

4.9t^2-14t+5.5=0

a = 4.9; b = -14; c = +5.5;
Δ = b2-4ac
Δ = -142-4·4.9·5.5
Δ = 88.2
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{-(-14)-\sqrt{88.2}}{2*4.9}=\frac{14-\sqrt{88.2}}{9.8}
$
$t_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-14)+\sqrt{88.2}}{2*4.9}=\frac{14+\sqrt{88.2}}{9.8}
$