t^2-20t+21=0

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Solution for t^2-20t+21=0 equation:


Simplifying
t2 + -20t + 21 = 0

Reorder the terms:
21 + -20t + t2 = 0

Solving
21 + -20t + t2 = 0

Solving for variable 't'.

Begin completing the square.

Move the constant term to the right:

Add '-21' to each side of the equation.
21 + -20t + -21 + t2 = 0 + -21

Reorder the terms:
21 + -21 + -20t + t2 = 0 + -21

Combine like terms: 21 + -21 = 0
0 + -20t + t2 = 0 + -21
-20t + t2 = 0 + -21

Combine like terms: 0 + -21 = -21
-20t + t2 = -21

The t term is -20t.  Take half its coefficient (-10).
Square it (100) and add it to both sides.

Add '100' to each side of the equation.
-20t + 100 + t2 = -21 + 100

Reorder the terms:
100 + -20t + t2 = -21 + 100

Combine like terms: -21 + 100 = 79
100 + -20t + t2 = 79

Factor a perfect square on the left side:
(t + -10)(t + -10) = 79

Calculate the square root of the right side: 8.888194417

Break this problem into two subproblems by setting 
(t + -10) equal to 8.888194417 and -8.888194417.

Subproblem 1

t + -10 = 8.888194417 Simplifying t + -10 = 8.888194417 Reorder the terms: -10 + t = 8.888194417 Solving -10 + t = 8.888194417 Solving for variable 't'. Move all terms containing t to the left, all other terms to the right. Add '10' to each side of the equation. -10 + 10 + t = 8.888194417 + 10 Combine like terms: -10 + 10 = 0 0 + t = 8.888194417 + 10 t = 8.888194417 + 10 Combine like terms: 8.888194417 + 10 = 18.888194417 t = 18.888194417 Simplifying t = 18.888194417

Subproblem 2

t + -10 = -8.888194417 Simplifying t + -10 = -8.888194417 Reorder the terms: -10 + t = -8.888194417 Solving -10 + t = -8.888194417 Solving for variable 't'. Move all terms containing t to the left, all other terms to the right. Add '10' to each side of the equation. -10 + 10 + t = -8.888194417 + 10 Combine like terms: -10 + 10 = 0 0 + t = -8.888194417 + 10 t = -8.888194417 + 10 Combine like terms: -8.888194417 + 10 = 1.111805583 t = 1.111805583 Simplifying t = 1.111805583

Solution

The solution to the problem is based on the solutions from the subproblems. t = {18.888194417, 1.111805583}

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