7x(3x+1)-3=9

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Solution for 7x(3x+1)-3=9 equation:


Simplifying
7x(3x + 1) + -3 = 9

Reorder the terms:
7x(1 + 3x) + -3 = 9
(1 * 7x + 3x * 7x) + -3 = 9
(7x + 21x2) + -3 = 9

Reorder the terms:
-3 + 7x + 21x2 = 9

Solving
-3 + 7x + 21x2 = 9

Solving for variable 'x'.

Reorder the terms:
-3 + -9 + 7x + 21x2 = 9 + -9

Combine like terms: -3 + -9 = -12
-12 + 7x + 21x2 = 9 + -9

Combine like terms: 9 + -9 = 0
-12 + 7x + 21x2 = 0

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

Divide each side by '21'.
-0.5714285714 + 0.3333333333x + x2 = 0

Move the constant term to the right:

Add '0.5714285714' to each side of the equation.
-0.5714285714 + 0.3333333333x + 0.5714285714 + x2 = 0 + 0.5714285714

Reorder the terms:
-0.5714285714 + 0.5714285714 + 0.3333333333x + x2 = 0 + 0.5714285714

Combine like terms: -0.5714285714 + 0.5714285714 = 0.0000000000
0.0000000000 + 0.3333333333x + x2 = 0 + 0.5714285714
0.3333333333x + x2 = 0 + 0.5714285714

Combine like terms: 0 + 0.5714285714 = 0.5714285714
0.3333333333x + x2 = 0.5714285714

The x term is 0.3333333333x.  Take half its coefficient (0.1666666667).
Square it (0.02777777779) and add it to both sides.

Add '0.02777777779' to each side of the equation.
0.3333333333x + 0.02777777779 + x2 = 0.5714285714 + 0.02777777779

Reorder the terms:
0.02777777779 + 0.3333333333x + x2 = 0.5714285714 + 0.02777777779

Combine like terms: 0.5714285714 + 0.02777777779 = 0.59920634919
0.02777777779 + 0.3333333333x + x2 = 0.59920634919

Factor a perfect square on the left side:
(x + 0.1666666667)(x + 0.1666666667) = 0.59920634919

Calculate the square root of the right side: 0.7740842

Break this problem into two subproblems by setting 
(x + 0.1666666667) equal to 0.7740842 and -0.7740842.

Subproblem 1

x + 0.1666666667 = 0.7740842 Simplifying x + 0.1666666667 = 0.7740842 Reorder the terms: 0.1666666667 + x = 0.7740842 Solving 0.1666666667 + x = 0.7740842 Solving for variable 'x'. Move all terms containing x to the left, all other terms to the right. Add '-0.1666666667' to each side of the equation. 0.1666666667 + -0.1666666667 + x = 0.7740842 + -0.1666666667 Combine like terms: 0.1666666667 + -0.1666666667 = 0.0000000000 0.0000000000 + x = 0.7740842 + -0.1666666667 x = 0.7740842 + -0.1666666667 Combine like terms: 0.7740842 + -0.1666666667 = 0.6074175333 x = 0.6074175333 Simplifying x = 0.6074175333

Subproblem 2

x + 0.1666666667 = -0.7740842 Simplifying x + 0.1666666667 = -0.7740842 Reorder the terms: 0.1666666667 + x = -0.7740842 Solving 0.1666666667 + x = -0.7740842 Solving for variable 'x'. Move all terms containing x to the left, all other terms to the right. Add '-0.1666666667' to each side of the equation. 0.1666666667 + -0.1666666667 + x = -0.7740842 + -0.1666666667 Combine like terms: 0.1666666667 + -0.1666666667 = 0.0000000000 0.0000000000 + x = -0.7740842 + -0.1666666667 x = -0.7740842 + -0.1666666667 Combine like terms: -0.7740842 + -0.1666666667 = -0.9407508667 x = -0.9407508667 Simplifying x = -0.9407508667

Solution

The solution to the problem is based on the solutions from the subproblems. x = {0.6074175333, -0.9407508667}

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