u^2+28u=31

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Solution for u^2+28u=31 equation:


Simplifying
u2 + 28u = 31

Reorder the terms:
28u + u2 = 31

Solving
28u + u2 = 31

Solving for variable 'u'.

Reorder the terms:
-31 + 28u + u2 = 31 + -31

Combine like terms: 31 + -31 = 0
-31 + 28u + u2 = 0

Begin completing the square.

Move the constant term to the right:

Add '31' to each side of the equation.
-31 + 28u + 31 + u2 = 0 + 31

Reorder the terms:
-31 + 31 + 28u + u2 = 0 + 31

Combine like terms: -31 + 31 = 0
0 + 28u + u2 = 0 + 31
28u + u2 = 0 + 31

Combine like terms: 0 + 31 = 31
28u + u2 = 31

The u term is 28u.  Take half its coefficient (14).
Square it (196) and add it to both sides.

Add '196' to each side of the equation.
28u + 196 + u2 = 31 + 196

Reorder the terms:
196 + 28u + u2 = 31 + 196

Combine like terms: 31 + 196 = 227
196 + 28u + u2 = 227

Factor a perfect square on the left side:
(u + 14)(u + 14) = 227

Calculate the square root of the right side: 15.066519173

Break this problem into two subproblems by setting 
(u + 14) equal to 15.066519173 and -15.066519173.

Subproblem 1

u + 14 = 15.066519173 Simplifying u + 14 = 15.066519173 Reorder the terms: 14 + u = 15.066519173 Solving 14 + u = 15.066519173 Solving for variable 'u'. Move all terms containing u to the left, all other terms to the right. Add '-14' to each side of the equation. 14 + -14 + u = 15.066519173 + -14 Combine like terms: 14 + -14 = 0 0 + u = 15.066519173 + -14 u = 15.066519173 + -14 Combine like terms: 15.066519173 + -14 = 1.066519173 u = 1.066519173 Simplifying u = 1.066519173

Subproblem 2

u + 14 = -15.066519173 Simplifying u + 14 = -15.066519173 Reorder the terms: 14 + u = -15.066519173 Solving 14 + u = -15.066519173 Solving for variable 'u'. Move all terms containing u to the left, all other terms to the right. Add '-14' to each side of the equation. 14 + -14 + u = -15.066519173 + -14 Combine like terms: 14 + -14 = 0 0 + u = -15.066519173 + -14 u = -15.066519173 + -14 Combine like terms: -15.066519173 + -14 = -29.066519173 u = -29.066519173 Simplifying u = -29.066519173

Solution

The solution to the problem is based on the solutions from the subproblems. u = {1.066519173, -29.066519173}

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