2t^2+4t=-1

Solution for 2t^2+4t=-1 equation:

Simplifying
2t2 + 4t = -1

Reorder the terms:
4t + 2t2 = -1

Solving
4t + 2t2 = -1

Solving for variable 't'.

Reorder the terms:
1 + 4t + 2t2 = -1 + 1

Combine like terms: -1 + 1 = 0
1 + 4t + 2t2 = 0

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

Divide each side by '2'.
0.5 + 2t + t2 = 0

Move the constant term to the right:

Add '-0.5' to each side of the equation.
0.5 + 2t + -0.5 + t2 = 0 + -0.5

Reorder the terms:
0.5 + -0.5 + 2t + t2 = 0 + -0.5

Combine like terms: 0.5 + -0.5 = 0.0
0.0 + 2t + t2 = 0 + -0.5
2t + t2 = 0 + -0.5

Combine like terms: 0 + -0.5 = -0.5
2t + t2 = -0.5

The t term is 2t.  Take half its coefficient (1).
Square it (1) and add it to both sides.

Add '1' to each side of the equation.
2t + 1 + t2 = -0.5 + 1

Reorder the terms:
1 + 2t + t2 = -0.5 + 1

Combine like terms: -0.5 + 1 = 0.5
1 + 2t + t2 = 0.5

Factor a perfect square on the left side:
(t + 1)(t + 1) = 0.5

Calculate the square root of the right side: 0.707106781

Break this problem into two subproblems by setting 
(t + 1) equal to 0.707106781 and -0.707106781.

Subproblem 1
t + 1 = 0.707106781

Simplifying
t + 1 = 0.707106781

Reorder the terms:
1 + t = 0.707106781

Solving
1 + t = 0.707106781

Solving for variable 't'.

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

Add '-1' to each side of the equation.
1 + -1 + t = 0.707106781 + -1

Combine like terms: 1 + -1 = 0
0 + t = 0.707106781 + -1
t = 0.707106781 + -1

Combine like terms: 0.707106781 + -1 = -0.292893219
t = -0.292893219

Simplifying
t = -0.292893219

Subproblem 2
t + 1 = -0.707106781

Simplifying
t + 1 = -0.707106781

Reorder the terms:
1 + t = -0.707106781

Solving
1 + t = -0.707106781

Solving for variable 't'.

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

Add '-1' to each side of the equation.
1 + -1 + t = -0.707106781 + -1

Combine like terms: 1 + -1 = 0
0 + t = -0.707106781 + -1
t = -0.707106781 + -1

Combine like terms: -0.707106781 + -1 = -1.707106781
t = -1.707106781

Simplifying
t = -1.707106781

Solution
The solution to the problem is based on the solutions
from the subproblems.
t = {-0.292893219, -1.707106781}