x^2-8x+7=9

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Solution for x^2-8x+7=9 equation:


Simplifying
x2 + -8x + 7 = 9

Reorder the terms:
7 + -8x + x2 = 9

Solving
7 + -8x + x2 = 9

Solving for variable 'x'.

Reorder the terms:
7 + -9 + -8x + x2 = 9 + -9

Combine like terms: 7 + -9 = -2
-2 + -8x + x2 = 9 + -9

Combine like terms: 9 + -9 = 0
-2 + -8x + x2 = 0

Begin completing the square.

Move the constant term to the right:

Add '2' to each side of the equation.
-2 + -8x + 2 + x2 = 0 + 2

Reorder the terms:
-2 + 2 + -8x + x2 = 0 + 2

Combine like terms: -2 + 2 = 0
0 + -8x + x2 = 0 + 2
-8x + x2 = 0 + 2

Combine like terms: 0 + 2 = 2
-8x + x2 = 2

The x term is -8x.  Take half its coefficient (-4).
Square it (16) and add it to both sides.

Add '16' to each side of the equation.
-8x + 16 + x2 = 2 + 16

Reorder the terms:
16 + -8x + x2 = 2 + 16

Combine like terms: 2 + 16 = 18
16 + -8x + x2 = 18

Factor a perfect square on the left side:
(x + -4)(x + -4) = 18

Calculate the square root of the right side: 4.242640687

Break this problem into two subproblems by setting 
(x + -4) equal to 4.242640687 and -4.242640687.

Subproblem 1

x + -4 = 4.242640687 Simplifying x + -4 = 4.242640687 Reorder the terms: -4 + x = 4.242640687 Solving -4 + x = 4.242640687 Solving for variable 'x'. Move all terms containing x to the left, all other terms to the right. Add '4' to each side of the equation. -4 + 4 + x = 4.242640687 + 4 Combine like terms: -4 + 4 = 0 0 + x = 4.242640687 + 4 x = 4.242640687 + 4 Combine like terms: 4.242640687 + 4 = 8.242640687 x = 8.242640687 Simplifying x = 8.242640687

Subproblem 2

x + -4 = -4.242640687 Simplifying x + -4 = -4.242640687 Reorder the terms: -4 + x = -4.242640687 Solving -4 + x = -4.242640687 Solving for variable 'x'. Move all terms containing x to the left, all other terms to the right. Add '4' to each side of the equation. -4 + 4 + x = -4.242640687 + 4 Combine like terms: -4 + 4 = 0 0 + x = -4.242640687 + 4 x = -4.242640687 + 4 Combine like terms: -4.242640687 + 4 = -0.242640687 x = -0.242640687 Simplifying x = -0.242640687

Solution

The solution to the problem is based on the solutions from the subproblems. x = {8.242640687, -0.242640687}

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