25x^2-20x+9=81

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Solution for 25x^2-20x+9=81 equation:


Simplifying
25x2 + -20x + 9 = 81

Reorder the terms:
9 + -20x + 25x2 = 81

Solving
9 + -20x + 25x2 = 81

Solving for variable 'x'.

Reorder the terms:
9 + -81 + -20x + 25x2 = 81 + -81

Combine like terms: 9 + -81 = -72
-72 + -20x + 25x2 = 81 + -81

Combine like terms: 81 + -81 = 0
-72 + -20x + 25x2 = 0

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

Divide each side by '25'.
-2.88 + -0.8x + x2 = 0

Move the constant term to the right:

Add '2.88' to each side of the equation.
-2.88 + -0.8x + 2.88 + x2 = 0 + 2.88

Reorder the terms:
-2.88 + 2.88 + -0.8x + x2 = 0 + 2.88

Combine like terms: -2.88 + 2.88 = 0.00
0.00 + -0.8x + x2 = 0 + 2.88
-0.8x + x2 = 0 + 2.88

Combine like terms: 0 + 2.88 = 2.88
-0.8x + x2 = 2.88

The x term is -0.8x.  Take half its coefficient (-0.4).
Square it (0.16) and add it to both sides.

Add '0.16' to each side of the equation.
-0.8x + 0.16 + x2 = 2.88 + 0.16

Reorder the terms:
0.16 + -0.8x + x2 = 2.88 + 0.16

Combine like terms: 2.88 + 0.16 = 3.04
0.16 + -0.8x + x2 = 3.04

Factor a perfect square on the left side:
(x + -0.4)(x + -0.4) = 3.04

Calculate the square root of the right side: 1.743559577

Break this problem into two subproblems by setting 
(x + -0.4) equal to 1.743559577 and -1.743559577.

Subproblem 1

x + -0.4 = 1.743559577 Simplifying x + -0.4 = 1.743559577 Reorder the terms: -0.4 + x = 1.743559577 Solving -0.4 + x = 1.743559577 Solving for variable 'x'. Move all terms containing x to the left, all other terms to the right. Add '0.4' to each side of the equation. -0.4 + 0.4 + x = 1.743559577 + 0.4 Combine like terms: -0.4 + 0.4 = 0.0 0.0 + x = 1.743559577 + 0.4 x = 1.743559577 + 0.4 Combine like terms: 1.743559577 + 0.4 = 2.143559577 x = 2.143559577 Simplifying x = 2.143559577

Subproblem 2

x + -0.4 = -1.743559577 Simplifying x + -0.4 = -1.743559577 Reorder the terms: -0.4 + x = -1.743559577 Solving -0.4 + x = -1.743559577 Solving for variable 'x'. Move all terms containing x to the left, all other terms to the right. Add '0.4' to each side of the equation. -0.4 + 0.4 + x = -1.743559577 + 0.4 Combine like terms: -0.4 + 0.4 = 0.0 0.0 + x = -1.743559577 + 0.4 x = -1.743559577 + 0.4 Combine like terms: -1.743559577 + 0.4 = -1.343559577 x = -1.343559577 Simplifying x = -1.343559577

Solution

The solution to the problem is based on the solutions from the subproblems. x = {2.143559577, -1.343559577}

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