140=.81t^2

Solution for 140=.81t^2 equation:

Simplifying
140 = 0.81t2

Solving
140 = 0.81t2

Solving for variable 't'.

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

Add '-0.81t2' to each side of the equation.
140 + -0.81t2 = 0.81t2 + -0.81t2

Combine like terms: 0.81t2 + -0.81t2 = 0.00
140 + -0.81t2 = 0.00

Add '-140' to each side of the equation.
140 + -140 + -0.81t2 = 0.00 + -140

Combine like terms: 140 + -140 = 0
0 + -0.81t2 = 0.00 + -140
-0.81t2 = 0.00 + -140

Combine like terms: 0.00 + -140 = -140
-0.81t2 = -140

Divide each side by '-0.81'.
t2 = 172.8395062

Simplifying
t2 = 172.8395062

Take the square root of each side:
t = {-13.146843963, 13.146843963}