2x^2+7x=40

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Solution for 2x^2+7x=40 equation:


Simplifying
2x2 + 7x = 40

Reorder the terms:
7x + 2x2 = 40

Solving
7x + 2x2 = 40

Solving for variable 'x'.

Reorder the terms:
-40 + 7x + 2x2 = 40 + -40

Combine like terms: 40 + -40 = 0
-40 + 7x + 2x2 = 0

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

Divide each side by '2'.
-20 + 3.5x + x2 = 0

Move the constant term to the right:

Add '20' to each side of the equation.
-20 + 3.5x + 20 + x2 = 0 + 20

Reorder the terms:
-20 + 20 + 3.5x + x2 = 0 + 20

Combine like terms: -20 + 20 = 0
0 + 3.5x + x2 = 0 + 20
3.5x + x2 = 0 + 20

Combine like terms: 0 + 20 = 20
3.5x + x2 = 20

The x term is 3.5x.  Take half its coefficient (1.75).
Square it (3.0625) and add it to both sides.

Add '3.0625' to each side of the equation.
3.5x + 3.0625 + x2 = 20 + 3.0625

Reorder the terms:
3.0625 + 3.5x + x2 = 20 + 3.0625

Combine like terms: 20 + 3.0625 = 23.0625
3.0625 + 3.5x + x2 = 23.0625

Factor a perfect square on the left side:
(x + 1.75)(x + 1.75) = 23.0625

Calculate the square root of the right side: 4.802343178

Break this problem into two subproblems by setting 
(x + 1.75) equal to 4.802343178 and -4.802343178.

Subproblem 1

x + 1.75 = 4.802343178 Simplifying x + 1.75 = 4.802343178 Reorder the terms: 1.75 + x = 4.802343178 Solving 1.75 + x = 4.802343178 Solving for variable 'x'. Move all terms containing x to the left, all other terms to the right. Add '-1.75' to each side of the equation. 1.75 + -1.75 + x = 4.802343178 + -1.75 Combine like terms: 1.75 + -1.75 = 0.00 0.00 + x = 4.802343178 + -1.75 x = 4.802343178 + -1.75 Combine like terms: 4.802343178 + -1.75 = 3.052343178 x = 3.052343178 Simplifying x = 3.052343178

Subproblem 2

x + 1.75 = -4.802343178 Simplifying x + 1.75 = -4.802343178 Reorder the terms: 1.75 + x = -4.802343178 Solving 1.75 + x = -4.802343178 Solving for variable 'x'. Move all terms containing x to the left, all other terms to the right. Add '-1.75' to each side of the equation. 1.75 + -1.75 + x = -4.802343178 + -1.75 Combine like terms: 1.75 + -1.75 = 0.00 0.00 + x = -4.802343178 + -1.75 x = -4.802343178 + -1.75 Combine like terms: -4.802343178 + -1.75 = -6.552343178 x = -6.552343178 Simplifying x = -6.552343178

Solution

The solution to the problem is based on the solutions from the subproblems. x = {3.052343178, -6.552343178}

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