-4.9t^2+9t+700=0

Solution for -4.9t^2+9t+700=0 equation:

-4.9t^2+9t+700=0

a = -4.9; b = 9; c = +700;
Δ = b2-4ac
Δ = 92-4·(-4.9)·700
Δ = 13801
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:

$\sqrt{\Delta}=\sqrt{13801}=\sqrt{1*13801}=\sqrt{1}*\sqrt{13801}=1\sqrt{13801}$
$t_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(9)-1\sqrt{13801}}{2*-4.9}=\frac{-9-1\sqrt{13801}}{-9.8}
$
$t_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(9)+1\sqrt{13801}}{2*-4.9}=\frac{-9+1\sqrt{13801}}{-9.8}
$