0=-2t^2+8t+25

Solution for 0=-2t^2+8t+25 equation:

0=-2t^2+8t+25

We move all terms to the left:

0-(-2t^2+8t+25)=0

We add all the numbers together, and all the variables

-(-2t^2+8t+25)=0

We get rid of parentheses

2t^2-8t-25=0

a = 2; b = -8; c = -25;
Δ = b2-4ac
Δ = -82-4·2·(-25)
Δ = 264
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:

$\sqrt{\Delta}=\sqrt{264}=\sqrt{4*66}=\sqrt{4}*\sqrt{66}=2\sqrt{66}$
$t_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-8)-2\sqrt{66}}{2*2}=\frac{8-2\sqrt{66}}{4}
$
$t_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-8)+2\sqrt{66}}{2*2}=\frac{8+2\sqrt{66}}{4}
$