x^2-9x=-4

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Solution for x^2-9x=-4 equation:


Simplifying
x2 + -9x = -4

Reorder the terms:
-9x + x2 = -4

Solving
-9x + x2 = -4

Solving for variable 'x'.

Reorder the terms:
4 + -9x + x2 = -4 + 4

Combine like terms: -4 + 4 = 0
4 + -9x + x2 = 0

Begin completing the square.

Move the constant term to the right:

Add '-4' to each side of the equation.
4 + -9x + -4 + x2 = 0 + -4

Reorder the terms:
4 + -4 + -9x + x2 = 0 + -4

Combine like terms: 4 + -4 = 0
0 + -9x + x2 = 0 + -4
-9x + x2 = 0 + -4

Combine like terms: 0 + -4 = -4
-9x + x2 = -4

The x term is -9x.  Take half its coefficient (-4.5).
Square it (20.25) and add it to both sides.

Add '20.25' to each side of the equation.
-9x + 20.25 + x2 = -4 + 20.25

Reorder the terms:
20.25 + -9x + x2 = -4 + 20.25

Combine like terms: -4 + 20.25 = 16.25
20.25 + -9x + x2 = 16.25

Factor a perfect square on the left side:
(x + -4.5)(x + -4.5) = 16.25

Calculate the square root of the right side: 4.031128874

Break this problem into two subproblems by setting 
(x + -4.5) equal to 4.031128874 and -4.031128874.

Subproblem 1

x + -4.5 = 4.031128874 Simplifying x + -4.5 = 4.031128874 Reorder the terms: -4.5 + x = 4.031128874 Solving -4.5 + x = 4.031128874 Solving for variable 'x'. Move all terms containing x to the left, all other terms to the right. Add '4.5' to each side of the equation. -4.5 + 4.5 + x = 4.031128874 + 4.5 Combine like terms: -4.5 + 4.5 = 0.0 0.0 + x = 4.031128874 + 4.5 x = 4.031128874 + 4.5 Combine like terms: 4.031128874 + 4.5 = 8.531128874 x = 8.531128874 Simplifying x = 8.531128874

Subproblem 2

x + -4.5 = -4.031128874 Simplifying x + -4.5 = -4.031128874 Reorder the terms: -4.5 + x = -4.031128874 Solving -4.5 + x = -4.031128874 Solving for variable 'x'. Move all terms containing x to the left, all other terms to the right. Add '4.5' to each side of the equation. -4.5 + 4.5 + x = -4.031128874 + 4.5 Combine like terms: -4.5 + 4.5 = 0.0 0.0 + x = -4.031128874 + 4.5 x = -4.031128874 + 4.5 Combine like terms: -4.031128874 + 4.5 = 0.468871126 x = 0.468871126 Simplifying x = 0.468871126

Solution

The solution to the problem is based on the solutions from the subproblems. x = {8.531128874, 0.468871126}

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