7n^2+4n-40=0

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Solution for 7n^2+4n-40=0 equation:


Simplifying
7n2 + 4n + -40 = 0

Reorder the terms:
-40 + 4n + 7n2 = 0

Solving
-40 + 4n + 7n2 = 0

Solving for variable 'n'.

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

Divide each side by '7'.
-5.714285714 + 0.5714285714n + n2 = 0

Move the constant term to the right:

Add '5.714285714' to each side of the equation.
-5.714285714 + 0.5714285714n + 5.714285714 + n2 = 0 + 5.714285714

Reorder the terms:
-5.714285714 + 5.714285714 + 0.5714285714n + n2 = 0 + 5.714285714

Combine like terms: -5.714285714 + 5.714285714 = 0.000000000
0.000000000 + 0.5714285714n + n2 = 0 + 5.714285714
0.5714285714n + n2 = 0 + 5.714285714

Combine like terms: 0 + 5.714285714 = 5.714285714
0.5714285714n + n2 = 5.714285714

The n term is 0.5714285714n.  Take half its coefficient (0.2857142857).
Square it (0.08163265305) and add it to both sides.

Add '0.08163265305' to each side of the equation.
0.5714285714n + 0.08163265305 + n2 = 5.714285714 + 0.08163265305

Reorder the terms:
0.08163265305 + 0.5714285714n + n2 = 5.714285714 + 0.08163265305

Combine like terms: 5.714285714 + 0.08163265305 = 5.79591836705
0.08163265305 + 0.5714285714n + n2 = 5.79591836705

Factor a perfect square on the left side:
(n + 0.2857142857)(n + 0.2857142857) = 5.79591836705

Calculate the square root of the right side: 2.407471364

Break this problem into two subproblems by setting 
(n + 0.2857142857) equal to 2.407471364 and -2.407471364.

Subproblem 1

n + 0.2857142857 = 2.407471364 Simplifying n + 0.2857142857 = 2.407471364 Reorder the terms: 0.2857142857 + n = 2.407471364 Solving 0.2857142857 + n = 2.407471364 Solving for variable 'n'. Move all terms containing n to the left, all other terms to the right. Add '-0.2857142857' to each side of the equation. 0.2857142857 + -0.2857142857 + n = 2.407471364 + -0.2857142857 Combine like terms: 0.2857142857 + -0.2857142857 = 0.0000000000 0.0000000000 + n = 2.407471364 + -0.2857142857 n = 2.407471364 + -0.2857142857 Combine like terms: 2.407471364 + -0.2857142857 = 2.1217570783 n = 2.1217570783 Simplifying n = 2.1217570783

Subproblem 2

n + 0.2857142857 = -2.407471364 Simplifying n + 0.2857142857 = -2.407471364 Reorder the terms: 0.2857142857 + n = -2.407471364 Solving 0.2857142857 + n = -2.407471364 Solving for variable 'n'. Move all terms containing n to the left, all other terms to the right. Add '-0.2857142857' to each side of the equation. 0.2857142857 + -0.2857142857 + n = -2.407471364 + -0.2857142857 Combine like terms: 0.2857142857 + -0.2857142857 = 0.0000000000 0.0000000000 + n = -2.407471364 + -0.2857142857 n = -2.407471364 + -0.2857142857 Combine like terms: -2.407471364 + -0.2857142857 = -2.6931856497 n = -2.6931856497 Simplifying n = -2.6931856497

Solution

The solution to the problem is based on the solutions from the subproblems. n = {2.1217570783, -2.6931856497}

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