42=x^2-7x+4

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Solution for 42=x^2-7x+4 equation:


Simplifying
42 = x2 + -7x + 4

Reorder the terms:
42 = 4 + -7x + x2

Solving
42 = 4 + -7x + x2

Solving for variable 'x'.

Combine like terms: 42 + -4 = 38
38 + 7x + -1x2 = 4 + -7x + x2 + -4 + 7x + -1x2

Reorder the terms:
38 + 7x + -1x2 = 4 + -4 + -7x + 7x + x2 + -1x2

Combine like terms: 4 + -4 = 0
38 + 7x + -1x2 = 0 + -7x + 7x + x2 + -1x2
38 + 7x + -1x2 = -7x + 7x + x2 + -1x2

Combine like terms: -7x + 7x = 0
38 + 7x + -1x2 = 0 + x2 + -1x2
38 + 7x + -1x2 = x2 + -1x2

Combine like terms: x2 + -1x2 = 0
38 + 7x + -1x2 = 0

Begin completing the square.  Divide all terms by
-1 the coefficient of the squared term: 

Divide each side by '-1'.
-38 + -7x + x2 = 0

Move the constant term to the right:

Add '38' to each side of the equation.
-38 + -7x + 38 + x2 = 0 + 38

Reorder the terms:
-38 + 38 + -7x + x2 = 0 + 38

Combine like terms: -38 + 38 = 0
0 + -7x + x2 = 0 + 38
-7x + x2 = 0 + 38

Combine like terms: 0 + 38 = 38
-7x + x2 = 38

The x term is -7x.  Take half its coefficient (-3.5).
Square it (12.25) and add it to both sides.

Add '12.25' to each side of the equation.
-7x + 12.25 + x2 = 38 + 12.25

Reorder the terms:
12.25 + -7x + x2 = 38 + 12.25

Combine like terms: 38 + 12.25 = 50.25
12.25 + -7x + x2 = 50.25

Factor a perfect square on the left side:
(x + -3.5)(x + -3.5) = 50.25

Calculate the square root of the right side: 7.088723439

Break this problem into two subproblems by setting 
(x + -3.5) equal to 7.088723439 and -7.088723439.

Subproblem 1

x + -3.5 = 7.088723439 Simplifying x + -3.5 = 7.088723439 Reorder the terms: -3.5 + x = 7.088723439 Solving -3.5 + x = 7.088723439 Solving for variable 'x'. Move all terms containing x to the left, all other terms to the right. Add '3.5' to each side of the equation. -3.5 + 3.5 + x = 7.088723439 + 3.5 Combine like terms: -3.5 + 3.5 = 0.0 0.0 + x = 7.088723439 + 3.5 x = 7.088723439 + 3.5 Combine like terms: 7.088723439 + 3.5 = 10.588723439 x = 10.588723439 Simplifying x = 10.588723439

Subproblem 2

x + -3.5 = -7.088723439 Simplifying x + -3.5 = -7.088723439 Reorder the terms: -3.5 + x = -7.088723439 Solving -3.5 + x = -7.088723439 Solving for variable 'x'. Move all terms containing x to the left, all other terms to the right. Add '3.5' to each side of the equation. -3.5 + 3.5 + x = -7.088723439 + 3.5 Combine like terms: -3.5 + 3.5 = 0.0 0.0 + x = -7.088723439 + 3.5 x = -7.088723439 + 3.5 Combine like terms: -7.088723439 + 3.5 = -3.588723439 x = -3.588723439 Simplifying x = -3.588723439

Solution

The solution to the problem is based on the solutions from the subproblems. x = {10.588723439, -3.588723439}

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