90=-16t^2+100

Solution for 90=-16t^2+100 equation:

Simplifying
90 = -16t2 + 100

Reorder the terms:
90 = 100 + -16t2

Solving
90 = 100 + -16t2

Solving for variable 't'.

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

Add '16t2' to each side of the equation.
90 + 16t2 = 100 + -16t2 + 16t2

Combine like terms: -16t2 + 16t2 = 0
90 + 16t2 = 100 + 0
90 + 16t2 = 100

Add '-90' to each side of the equation.
90 + -90 + 16t2 = 100 + -90

Combine like terms: 90 + -90 = 0
0 + 16t2 = 100 + -90
16t2 = 100 + -90

Combine like terms: 100 + -90 = 10
16t2 = 10

Divide each side by '16'.
t2 = 0.625

Simplifying
t2 = 0.625

Take the square root of each side:
t = {-0.790569415, 0.790569415}