40=.5t-4.9t^2

Solution for 40=.5t-4.9t^2 equation:

Simplifying
40 = 0.5t + -4.9t2

Solving
40 = 0.5t + -4.9t2

Solving for variable 't'.

Reorder the terms:
40 + -0.5t + 4.9t2 = 0.5t + -0.5t + -4.9t2 + 4.9t2

Combine like terms: 0.5t + -0.5t = 0.0
40 + -0.5t + 4.9t2 = 0.0 + -4.9t2 + 4.9t2
40 + -0.5t + 4.9t2 = -4.9t2 + 4.9t2

Combine like terms: -4.9t2 + 4.9t2 = 0.0
40 + -0.5t + 4.9t2 = 0.0

Begin completing the square.  Divide all terms by
4.9 the coefficient of the squared term: 

Divide each side by '4.9'.
8.163265306 + -0.1020408163t + t2 = 0

Move the constant term to the right:

Add '-8.163265306' to each side of the equation.
8.163265306 + -0.1020408163t + -8.163265306 + t2 = 0 + -8.163265306

Reorder the terms:
8.163265306 + -8.163265306 + -0.1020408163t + t2 = 0 + -8.163265306

Combine like terms: 8.163265306 + -8.163265306 = 0.000000000
0.000000000 + -0.1020408163t + t2 = 0 + -8.163265306
-0.1020408163t + t2 = 0 + -8.163265306

Combine like terms: 0 + -8.163265306 = -8.163265306
-0.1020408163t + t2 = -8.163265306

The t term is -0.1020408163t.  Take half its coefficient (-0.05102040815).
Square it (0.002603082048) and add it to both sides.

Add '0.002603082048' to each side of the equation.
-0.1020408163t + 0.002603082048 + t2 = -8.163265306 + 0.002603082048

Reorder the terms:
0.002603082048 + -0.1020408163t + t2 = -8.163265306 + 0.002603082048

Combine like terms: -8.163265306 + 0.002603082048 = -8.160662223952
0.002603082048 + -0.1020408163t + t2 = -8.160662223952

Factor a perfect square on the left side:
(t + -0.05102040815)(t + -0.05102040815) = -8.160662223952

Can't calculate square root of the right side.

The solution to this equation could not be determined.