0=-4.9t^2+70t+50

Solution for 0=-4.9t^2+70t+50 equation:

0=-4.9t^2+70t+50

We move all terms to the left:

0-(-4.9t^2+70t+50)=0

We add all the numbers together, and all the variables

-(-4.9t^2+70t+50)=0

We get rid of parentheses

4.9t^2-70t-50=0

a = 4.9; b = -70; c = -50;
Δ = b2-4ac
Δ = -702-4·4.9·(-50)
Δ = 5880
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:

$\sqrt{\Delta}=\sqrt{5880}=\sqrt{196*30}=\sqrt{196}*\sqrt{30}=14\sqrt{30}$
$t_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-70)-14\sqrt{30}}{2*4.9}=\frac{70-14\sqrt{30}}{9.8}
$
$t_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-70)+14\sqrt{30}}{2*4.9}=\frac{70+14\sqrt{30}}{9.8}
$