-4.9t^2+8t+70=0

Solution for -4.9t^2+8t+70=0 equation:

-4.9t^2+8t+70=0

a = -4.9; b = 8; c = +70;
Δ = b2-4ac
Δ = 82-4·(-4.9)·70
Δ = 1436
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:

$\sqrt{\Delta}=\sqrt{1436}=\sqrt{4*359}=\sqrt{4}*\sqrt{359}=2\sqrt{359}$
$t_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(8)-2\sqrt{359}}{2*-4.9}=\frac{-8-2\sqrt{359}}{-9.8}
$
$t_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(8)+2\sqrt{359}}{2*-4.9}=\frac{-8+2\sqrt{359}}{-9.8}
$