-4.9t^2+90t+5=250

Solution for -4.9t^2+90t+5=250 equation:

-4.9t^2+90t+5=250

We move all terms to the left:

-4.9t^2+90t+5-(250)=0

We add all the numbers together, and all the variables

-4.9t^2+90t-245=0

a = -4.9; b = 90; c = -245;
Δ = b2-4ac
Δ = 902-4·(-4.9)·(-245)
Δ = 3298
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{-(90)-\sqrt{3298}}{2*-4.9}=\frac{-90-\sqrt{3298}}{-9.8}
$
$t_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(90)+\sqrt{3298}}{2*-4.9}=\frac{-90+\sqrt{3298}}{-9.8}
$