0=4t^2-9t-40

Solution for 0=4t^2-9t-40 equation:

0=4t^2-9t-40

We move all terms to the left:

0-(4t^2-9t-40)=0

We add all the numbers together, and all the variables

-(4t^2-9t-40)=0

We get rid of parentheses

-4t^2+9t+40=0

a = -4; b = 9; c = +40;
Δ = b2-4ac
Δ = 92-4·(-4)·40
Δ = 721
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{-(9)-\sqrt{721}}{2*-4}=\frac{-9-\sqrt{721}}{-8}
$
$t_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(9)+\sqrt{721}}{2*-4}=\frac{-9+\sqrt{721}}{-8}
$