0=80-4*t-16*t^2

Solution for 0=80-4*t-16*t^2 equation:

Simplifying
0 = 80 + -4t + -16t2

Solving
0 = 80 + -4t + -16t2

Solving for variable 't'.

Combine like terms: 0 + -80 = -80
-80 + 4t + 16t2 = 80 + -4t + -16t2 + -80 + 4t + 16t2

Reorder the terms:
-80 + 4t + 16t2 = 80 + -80 + -4t + 4t + -16t2 + 16t2

Combine like terms: 80 + -80 = 0
-80 + 4t + 16t2 = 0 + -4t + 4t + -16t2 + 16t2
-80 + 4t + 16t2 = -4t + 4t + -16t2 + 16t2

Combine like terms: -4t + 4t = 0
-80 + 4t + 16t2 = 0 + -16t2 + 16t2
-80 + 4t + 16t2 = -16t2 + 16t2

Combine like terms: -16t2 + 16t2 = 0
-80 + 4t + 16t2 = 0

Factor out the Greatest Common Factor (GCF), '4'.
4(-20 + t + 4t2) = 0

Ignore the factor 4.
Subproblem 1
Set the factor '(-20 + t + 4t2)' equal to zero and attempt to solve:

Simplifying
-20 + t + 4t2 = 0

Solving
-20 + t + 4t2 = 0

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

Divide each side by '4'.
-5 + 0.25t + t2 = 0

Move the constant term to the right:

Add '5' to each side of the equation.
-5 + 0.25t + 5 + t2 = 0 + 5

Reorder the terms:
-5 + 5 + 0.25t + t2 = 0 + 5

Combine like terms: -5 + 5 = 0
0 + 0.25t + t2 = 0 + 5
0.25t + t2 = 0 + 5

Combine like terms: 0 + 5 = 5
0.25t + t2 = 5

The t term is t.  Take half its coefficient (0.5).
Square it (0.25) and add it to both sides.

Add '0.25' to each side of the equation.
0.25t + 0.25 + t2 = 5 + 0.25

Reorder the terms:
0.25 + 0.25t + t2 = 5 + 0.25

Combine like terms: 5 + 0.25 = 5.25
0.25 + 0.25t + t2 = 5.25

Factor a perfect square on the left side:
(t + 0.5)(t + 0.5) = 5.25

Calculate the square root of the right side: 2.291287847

Break this problem into two subproblems by setting 
(t + 0.5) equal to 2.291287847 and -2.291287847.

Subproblem 1
t + 0.5 = 2.291287847

Simplifying
t + 0.5 = 2.291287847

Reorder the terms:
0.5 + t = 2.291287847

Solving
0.5 + t = 2.291287847

Solving for variable 't'.

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

Add '-0.5' to each side of the equation.
0.5 + -0.5 + t = 2.291287847 + -0.5

Combine like terms: 0.5 + -0.5 = 0.0
0.0 + t = 2.291287847 + -0.5
t = 2.291287847 + -0.5

Combine like terms: 2.291287847 + -0.5 = 1.791287847
t = 1.791287847

Simplifying
t = 1.791287847

Subproblem 2
t + 0.5 = -2.291287847

Simplifying
t + 0.5 = -2.291287847

Reorder the terms:
0.5 + t = -2.291287847

Solving
0.5 + t = -2.291287847

Solving for variable 't'.

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

Add '-0.5' to each side of the equation.
0.5 + -0.5 + t = -2.291287847 + -0.5

Combine like terms: 0.5 + -0.5 = 0.0
0.0 + t = -2.291287847 + -0.5
t = -2.291287847 + -0.5

Combine like terms: -2.291287847 + -0.5 = -2.791287847
t = -2.791287847

Simplifying
t = -2.791287847

Solution
The solution to the problem is based on the solutions
from the subproblems.
t = {1.791287847, -2.791287847}
Solution
t = {1.791287847, -2.791287847}