7x^2+4x=28

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Solution for 7x^2+4x=28 equation:


Simplifying
7x2 + 4x = 28

Reorder the terms:
4x + 7x2 = 28

Solving
4x + 7x2 = 28

Solving for variable 'x'.

Reorder the terms:
-28 + 4x + 7x2 = 28 + -28

Combine like terms: 28 + -28 = 0
-28 + 4x + 7x2 = 0

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

Divide each side by '7'.
-4 + 0.5714285714x + x2 = 0

Move the constant term to the right:

Add '4' to each side of the equation.
-4 + 0.5714285714x + 4 + x2 = 0 + 4

Reorder the terms:
-4 + 4 + 0.5714285714x + x2 = 0 + 4

Combine like terms: -4 + 4 = 0
0 + 0.5714285714x + x2 = 0 + 4
0.5714285714x + x2 = 0 + 4

Combine like terms: 0 + 4 = 4
0.5714285714x + x2 = 4

The x term is 0.5714285714x.  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.
0.5714285714x + 0.08163265305 + x2 = 4 + 0.08163265305

Reorder the terms:
0.08163265305 + 0.5714285714x + x2 = 4 + 0.08163265305

Combine like terms: 4 + 0.08163265305 = 4.08163265305
0.08163265305 + 0.5714285714x + x2 = 4.08163265305

Factor a perfect square on the left side:
(x + 0.2857142857)(x + 0.2857142857) = 4.08163265305

Calculate the square root of the right side: 2.020305089

Break this problem into two subproblems by setting 
(x + 0.2857142857) equal to 2.020305089 and -2.020305089.

Subproblem 1

x + 0.2857142857 = 2.020305089 Simplifying x + 0.2857142857 = 2.020305089 Reorder the terms: 0.2857142857 + x = 2.020305089 Solving 0.2857142857 + x = 2.020305089 Solving for variable 'x'. Move all terms containing x to the left, all other terms to the right. Add '-0.2857142857' to each side of the equation. 0.2857142857 + -0.2857142857 + x = 2.020305089 + -0.2857142857 Combine like terms: 0.2857142857 + -0.2857142857 = 0.0000000000 0.0000000000 + x = 2.020305089 + -0.2857142857 x = 2.020305089 + -0.2857142857 Combine like terms: 2.020305089 + -0.2857142857 = 1.7345908033 x = 1.7345908033 Simplifying x = 1.7345908033

Subproblem 2

x + 0.2857142857 = -2.020305089 Simplifying x + 0.2857142857 = -2.020305089 Reorder the terms: 0.2857142857 + x = -2.020305089 Solving 0.2857142857 + x = -2.020305089 Solving for variable 'x'. Move all terms containing x to the left, all other terms to the right. Add '-0.2857142857' to each side of the equation. 0.2857142857 + -0.2857142857 + x = -2.020305089 + -0.2857142857 Combine like terms: 0.2857142857 + -0.2857142857 = 0.0000000000 0.0000000000 + x = -2.020305089 + -0.2857142857 x = -2.020305089 + -0.2857142857 Combine like terms: -2.020305089 + -0.2857142857 = -2.3060193747 x = -2.3060193747 Simplifying x = -2.3060193747

Solution

The solution to the problem is based on the solutions from the subproblems. x = {1.7345908033, -2.3060193747}

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