7y^2-2y-4=0

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Solution for 7y^2-2y-4=0 equation:


Simplifying
7y2 + -2y + -4 = 0

Reorder the terms:
-4 + -2y + 7y2 = 0

Solving
-4 + -2y + 7y2 = 0

Solving for variable 'y'.

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

Divide each side by '7'.
-0.5714285714 + -0.2857142857y + y2 = 0

Move the constant term to the right:

Add '0.5714285714' to each side of the equation.
-0.5714285714 + -0.2857142857y + 0.5714285714 + y2 = 0 + 0.5714285714

Reorder the terms:
-0.5714285714 + 0.5714285714 + -0.2857142857y + y2 = 0 + 0.5714285714

Combine like terms: -0.5714285714 + 0.5714285714 = 0.0000000000
0.0000000000 + -0.2857142857y + y2 = 0 + 0.5714285714
-0.2857142857y + y2 = 0 + 0.5714285714

Combine like terms: 0 + 0.5714285714 = 0.5714285714
-0.2857142857y + y2 = 0.5714285714

The y term is -0.2857142857y.  Take half its coefficient (-0.1428571429).
Square it (0.02040816328) and add it to both sides.

Add '0.02040816328' to each side of the equation.
-0.2857142857y + 0.02040816328 + y2 = 0.5714285714 + 0.02040816328

Reorder the terms:
0.02040816328 + -0.2857142857y + y2 = 0.5714285714 + 0.02040816328

Combine like terms: 0.5714285714 + 0.02040816328 = 0.59183673468
0.02040816328 + -0.2857142857y + y2 = 0.59183673468

Factor a perfect square on the left side:
(y + -0.1428571429)(y + -0.1428571429) = 0.59183673468

Calculate the square root of the right side: 0.769309258

Break this problem into two subproblems by setting 
(y + -0.1428571429) equal to 0.769309258 and -0.769309258.

Subproblem 1

y + -0.1428571429 = 0.769309258 Simplifying y + -0.1428571429 = 0.769309258 Reorder the terms: -0.1428571429 + y = 0.769309258 Solving -0.1428571429 + y = 0.769309258 Solving for variable 'y'. Move all terms containing y to the left, all other terms to the right. Add '0.1428571429' to each side of the equation. -0.1428571429 + 0.1428571429 + y = 0.769309258 + 0.1428571429 Combine like terms: -0.1428571429 + 0.1428571429 = 0.0000000000 0.0000000000 + y = 0.769309258 + 0.1428571429 y = 0.769309258 + 0.1428571429 Combine like terms: 0.769309258 + 0.1428571429 = 0.9121664009 y = 0.9121664009 Simplifying y = 0.9121664009

Subproblem 2

y + -0.1428571429 = -0.769309258 Simplifying y + -0.1428571429 = -0.769309258 Reorder the terms: -0.1428571429 + y = -0.769309258 Solving -0.1428571429 + y = -0.769309258 Solving for variable 'y'. Move all terms containing y to the left, all other terms to the right. Add '0.1428571429' to each side of the equation. -0.1428571429 + 0.1428571429 + y = -0.769309258 + 0.1428571429 Combine like terms: -0.1428571429 + 0.1428571429 = 0.0000000000 0.0000000000 + y = -0.769309258 + 0.1428571429 y = -0.769309258 + 0.1428571429 Combine like terms: -0.769309258 + 0.1428571429 = -0.6264521151 y = -0.6264521151 Simplifying y = -0.6264521151

Solution

The solution to the problem is based on the solutions from the subproblems. y = {0.9121664009, -0.6264521151}

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