25=0*t+0.5*9.8*t^2

Solution for 25=0*t+0.5*9.8*t^2 equation:

Simplifying
25 = 0t + 0.5 * 9.8t2

Anything times zero is zero.
25 = 0t + 0.5 * 9.8t2

Multiply 0.5 * 9.8
25 = 0 + 4.9t2
Remove the zero:
25 = 4.9t2

Solving
25 = 4.9t2

Solving for variable 't'.

Move all terms containing t to the left, all other terms to the right.

Add '-4.9t2' to each side of the equation.
25 + -4.9t2 = 4.9t2 + -4.9t2

Combine like terms: 4.9t2 + -4.9t2 = 0.0
25 + -4.9t2 = 0.0

Add '-25' to each side of the equation.
25 + -25 + -4.9t2 = 0.0 + -25

Combine like terms: 25 + -25 = 0
0 + -4.9t2 = 0.0 + -25
-4.9t2 = 0.0 + -25

Combine like terms: 0.0 + -25 = -25
-4.9t2 = -25

Divide each side by '-4.9'.
t2 = 5.102040816

Simplifying
t2 = 5.102040816

Take the square root of each side:
t = {-2.258769757, 2.258769757}