17.15t-4.9t^2=2.45

Solution for 17.15t-4.9t^2=2.45 equation:

17.15t-4.9t^2=2.45

We move all terms to the left:

17.15t-4.9t^2-(2.45)=0

We add all the numbers together, and all the variables

-4.9t^2+17.15t-2.45=0

a = -4.9; b = 17.15; c = -2.45;
Δ = b2-4ac
Δ = 17.152-4·(-4.9)·(-2.45)
Δ = 246.1025
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{-(17.15)-\sqrt{246.1025}}{2*-4.9}=\frac{-17.15-\sqrt{246.1025}}{-9.8}
$
$t_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(17.15)+\sqrt{246.1025}}{2*-4.9}=\frac{-17.15+\sqrt{246.1025}}{-9.8}
$