6=-4.9t^2+8.1t

Solution for 6=-4.9t^2+8.1t equation:

Simplifying
6 = -4.9t2 + 8.1t

Reorder the terms:
6 = 8.1t + -4.9t2

Solving
6 = 8.1t + -4.9t2

Solving for variable 't'.

Reorder the terms:
6 + -8.1t + 4.9t2 = 8.1t + -8.1t + -4.9t2 + 4.9t2

Combine like terms: 8.1t + -8.1t = 0.0
6 + -8.1t + 4.9t2 = 0.0 + -4.9t2 + 4.9t2
6 + -8.1t + 4.9t2 = -4.9t2 + 4.9t2

Combine like terms: -4.9t2 + 4.9t2 = 0.0
6 + -8.1t + 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'.
1.224489796 + -1.653061224t + t2 = 0

Move the constant term to the right:

Add '-1.224489796' to each side of the equation.
1.224489796 + -1.653061224t + -1.224489796 + t2 = 0 + -1.224489796

Reorder the terms:
1.224489796 + -1.224489796 + -1.653061224t + t2 = 0 + -1.224489796

Combine like terms: 1.224489796 + -1.224489796 = 0.000000000
0.000000000 + -1.653061224t + t2 = 0 + -1.224489796
-1.653061224t + t2 = 0 + -1.224489796

Combine like terms: 0 + -1.224489796 = -1.224489796
-1.653061224t + t2 = -1.224489796

The t term is -1.653061224t.  Take half its coefficient (-0.826530612).
Square it (0.6831528526) and add it to both sides.

Add '0.6831528526' to each side of the equation.
-1.653061224t + 0.6831528526 + t2 = -1.224489796 + 0.6831528526

Reorder the terms:
0.6831528526 + -1.653061224t + t2 = -1.224489796 + 0.6831528526

Combine like terms: -1.224489796 + 0.6831528526 = -0.5413369434
0.6831528526 + -1.653061224t + t2 = -0.5413369434

Factor a perfect square on the left side:
(t + -0.826530612)(t + -0.826530612) = -0.5413369434

Can't calculate square root of the right side.

The solution to this equation could not be determined.