7u^2-3u-7=0

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Solution for 7u^2-3u-7=0 equation:


Simplifying
7u2 + -3u + -7 = 0

Reorder the terms:
-7 + -3u + 7u2 = 0

Solving
-7 + -3u + 7u2 = 0

Solving for variable 'u'.

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

Divide each side by '7'.
-1 + -0.4285714286u + u2 = 0

Move the constant term to the right:

Add '1' to each side of the equation.
-1 + -0.4285714286u + 1 + u2 = 0 + 1

Reorder the terms:
-1 + 1 + -0.4285714286u + u2 = 0 + 1

Combine like terms: -1 + 1 = 0
0 + -0.4285714286u + u2 = 0 + 1
-0.4285714286u + u2 = 0 + 1

Combine like terms: 0 + 1 = 1
-0.4285714286u + u2 = 1

The u term is -0.4285714286u.  Take half its coefficient (-0.2142857143).
Square it (0.04591836735) and add it to both sides.

Add '0.04591836735' to each side of the equation.
-0.4285714286u + 0.04591836735 + u2 = 1 + 0.04591836735

Reorder the terms:
0.04591836735 + -0.4285714286u + u2 = 1 + 0.04591836735

Combine like terms: 1 + 0.04591836735 = 1.04591836735
0.04591836735 + -0.4285714286u + u2 = 1.04591836735

Factor a perfect square on the left side:
(u + -0.2142857143)(u + -0.2142857143) = 1.04591836735

Calculate the square root of the right side: 1.022701505

Break this problem into two subproblems by setting 
(u + -0.2142857143) equal to 1.022701505 and -1.022701505.

Subproblem 1

u + -0.2142857143 = 1.022701505 Simplifying u + -0.2142857143 = 1.022701505 Reorder the terms: -0.2142857143 + u = 1.022701505 Solving -0.2142857143 + u = 1.022701505 Solving for variable 'u'. Move all terms containing u to the left, all other terms to the right. Add '0.2142857143' to each side of the equation. -0.2142857143 + 0.2142857143 + u = 1.022701505 + 0.2142857143 Combine like terms: -0.2142857143 + 0.2142857143 = 0.0000000000 0.0000000000 + u = 1.022701505 + 0.2142857143 u = 1.022701505 + 0.2142857143 Combine like terms: 1.022701505 + 0.2142857143 = 1.2369872193 u = 1.2369872193 Simplifying u = 1.2369872193

Subproblem 2

u + -0.2142857143 = -1.022701505 Simplifying u + -0.2142857143 = -1.022701505 Reorder the terms: -0.2142857143 + u = -1.022701505 Solving -0.2142857143 + u = -1.022701505 Solving for variable 'u'. Move all terms containing u to the left, all other terms to the right. Add '0.2142857143' to each side of the equation. -0.2142857143 + 0.2142857143 + u = -1.022701505 + 0.2142857143 Combine like terms: -0.2142857143 + 0.2142857143 = 0.0000000000 0.0000000000 + u = -1.022701505 + 0.2142857143 u = -1.022701505 + 0.2142857143 Combine like terms: -1.022701505 + 0.2142857143 = -0.8084157907 u = -0.8084157907 Simplifying u = -0.8084157907

Solution

The solution to the problem is based on the solutions from the subproblems. u = {1.2369872193, -0.8084157907}

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