-4.9t^2+8t+170=0

Solution for -4.9t^2+8t+170=0 equation:

-4.9t^2+8t+170=0

a = -4.9; b = 8; c = +170;
Δ = b2-4ac
Δ = 82-4·(-4.9)·170
Δ = 3396
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$t_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$t_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

The end solution:

$\sqrt{\Delta}=\sqrt{3396}=\sqrt{4*849}=\sqrt{4}*\sqrt{849}=2\sqrt{849}$
$t_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(8)-2\sqrt{849}}{2*-4.9}=\frac{-8-2\sqrt{849}}{-9.8}
$
$t_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(8)+2\sqrt{849}}{2*-4.9}=\frac{-8+2\sqrt{849}}{-9.8}
$