7y^2-y-4=0

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


Simplifying
7y2 + -1y + -4 = 0

Reorder the terms:
-4 + -1y + 7y2 = 0

Solving
-4 + -1y + 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 + -0.1428571429y + y2 = 0

Move the constant term to the right:

Add '0.5714285714' to each side of the equation.
-0.5714285714 + -0.1428571429y + 0.5714285714 + y2 = 0 + 0.5714285714

Reorder the terms:
-0.5714285714 + 0.5714285714 + -0.1428571429y + y2 = 0 + 0.5714285714

Combine like terms: -0.5714285714 + 0.5714285714 = 0.0000000000
0.0000000000 + -0.1428571429y + y2 = 0 + 0.5714285714
-0.1428571429y + y2 = 0 + 0.5714285714

Combine like terms: 0 + 0.5714285714 = 0.5714285714
-0.1428571429y + y2 = 0.5714285714

The y term is -0.1428571429y.  Take half its coefficient (-0.07142857145).
Square it (0.005102040819) and add it to both sides.

Add '0.005102040819' to each side of the equation.
-0.1428571429y + 0.005102040819 + y2 = 0.5714285714 + 0.005102040819

Reorder the terms:
0.005102040819 + -0.1428571429y + y2 = 0.5714285714 + 0.005102040819

Combine like terms: 0.5714285714 + 0.005102040819 = 0.576530612219
0.005102040819 + -0.1428571429y + y2 = 0.576530612219

Factor a perfect square on the left side:
(y + -0.07142857145)(y + -0.07142857145) = 0.576530612219

Calculate the square root of the right side: 0.759296129

Break this problem into two subproblems by setting 
(y + -0.07142857145) equal to 0.759296129 and -0.759296129.

Subproblem 1

y + -0.07142857145 = 0.759296129 Simplifying y + -0.07142857145 = 0.759296129 Reorder the terms: -0.07142857145 + y = 0.759296129 Solving -0.07142857145 + y = 0.759296129 Solving for variable 'y'. Move all terms containing y to the left, all other terms to the right. Add '0.07142857145' to each side of the equation. -0.07142857145 + 0.07142857145 + y = 0.759296129 + 0.07142857145 Combine like terms: -0.07142857145 + 0.07142857145 = 0.00000000000 0.00000000000 + y = 0.759296129 + 0.07142857145 y = 0.759296129 + 0.07142857145 Combine like terms: 0.759296129 + 0.07142857145 = 0.83072470045 y = 0.83072470045 Simplifying y = 0.83072470045

Subproblem 2

y + -0.07142857145 = -0.759296129 Simplifying y + -0.07142857145 = -0.759296129 Reorder the terms: -0.07142857145 + y = -0.759296129 Solving -0.07142857145 + y = -0.759296129 Solving for variable 'y'. Move all terms containing y to the left, all other terms to the right. Add '0.07142857145' to each side of the equation. -0.07142857145 + 0.07142857145 + y = -0.759296129 + 0.07142857145 Combine like terms: -0.07142857145 + 0.07142857145 = 0.00000000000 0.00000000000 + y = -0.759296129 + 0.07142857145 y = -0.759296129 + 0.07142857145 Combine like terms: -0.759296129 + 0.07142857145 = -0.68786755755 y = -0.68786755755 Simplifying y = -0.68786755755

Solution

The solution to the problem is based on the solutions from the subproblems. y = {0.83072470045, -0.68786755755}

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