2w^2-5w-21=0

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Solution for 2w^2-5w-21=0 equation:


Simplifying
2w2 + -5w + -21 = 0

Reorder the terms:
-21 + -5w + 2w2 = 0

Solving
-21 + -5w + 2w2 = 0

Solving for variable 'w'.

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

Divide each side by '2'.
-10.5 + -2.5w + w2 = 0

Move the constant term to the right:

Add '10.5' to each side of the equation.
-10.5 + -2.5w + 10.5 + w2 = 0 + 10.5

Reorder the terms:
-10.5 + 10.5 + -2.5w + w2 = 0 + 10.5

Combine like terms: -10.5 + 10.5 = 0.0
0.0 + -2.5w + w2 = 0 + 10.5
-2.5w + w2 = 0 + 10.5

Combine like terms: 0 + 10.5 = 10.5
-2.5w + w2 = 10.5

The w term is -2.5w.  Take half its coefficient (-1.25).
Square it (1.5625) and add it to both sides.

Add '1.5625' to each side of the equation.
-2.5w + 1.5625 + w2 = 10.5 + 1.5625

Reorder the terms:
1.5625 + -2.5w + w2 = 10.5 + 1.5625

Combine like terms: 10.5 + 1.5625 = 12.0625
1.5625 + -2.5w + w2 = 12.0625

Factor a perfect square on the left side:
(w + -1.25)(w + -1.25) = 12.0625

Calculate the square root of the right side: 3.473110997

Break this problem into two subproblems by setting 
(w + -1.25) equal to 3.473110997 and -3.473110997.

Subproblem 1

w + -1.25 = 3.473110997 Simplifying w + -1.25 = 3.473110997 Reorder the terms: -1.25 + w = 3.473110997 Solving -1.25 + w = 3.473110997 Solving for variable 'w'. Move all terms containing w to the left, all other terms to the right. Add '1.25' to each side of the equation. -1.25 + 1.25 + w = 3.473110997 + 1.25 Combine like terms: -1.25 + 1.25 = 0.00 0.00 + w = 3.473110997 + 1.25 w = 3.473110997 + 1.25 Combine like terms: 3.473110997 + 1.25 = 4.723110997 w = 4.723110997 Simplifying w = 4.723110997

Subproblem 2

w + -1.25 = -3.473110997 Simplifying w + -1.25 = -3.473110997 Reorder the terms: -1.25 + w = -3.473110997 Solving -1.25 + w = -3.473110997 Solving for variable 'w'. Move all terms containing w to the left, all other terms to the right. Add '1.25' to each side of the equation. -1.25 + 1.25 + w = -3.473110997 + 1.25 Combine like terms: -1.25 + 1.25 = 0.00 0.00 + w = -3.473110997 + 1.25 w = -3.473110997 + 1.25 Combine like terms: -3.473110997 + 1.25 = -2.223110997 w = -2.223110997 Simplifying w = -2.223110997

Solution

The solution to the problem is based on the solutions from the subproblems. w = {4.723110997, -2.223110997}

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