4x^2-9x+9=21x

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Solution for 4x^2-9x+9=21x equation:


Simplifying
4x2 + -9x + 9 = 21x

Reorder the terms:
9 + -9x + 4x2 = 21x

Solving
9 + -9x + 4x2 = 21x

Solving for variable 'x'.

Reorder the terms:
9 + -9x + -21x + 4x2 = 21x + -21x

Combine like terms: -9x + -21x = -30x
9 + -30x + 4x2 = 21x + -21x

Combine like terms: 21x + -21x = 0
9 + -30x + 4x2 = 0

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

Divide each side by '4'.
2.25 + -7.5x + x2 = 0

Move the constant term to the right:

Add '-2.25' to each side of the equation.
2.25 + -7.5x + -2.25 + x2 = 0 + -2.25

Reorder the terms:
2.25 + -2.25 + -7.5x + x2 = 0 + -2.25

Combine like terms: 2.25 + -2.25 = 0.00
0.00 + -7.5x + x2 = 0 + -2.25
-7.5x + x2 = 0 + -2.25

Combine like terms: 0 + -2.25 = -2.25
-7.5x + x2 = -2.25

The x term is -7.5x.  Take half its coefficient (-3.75).
Square it (14.0625) and add it to both sides.

Add '14.0625' to each side of the equation.
-7.5x + 14.0625 + x2 = -2.25 + 14.0625

Reorder the terms:
14.0625 + -7.5x + x2 = -2.25 + 14.0625

Combine like terms: -2.25 + 14.0625 = 11.8125
14.0625 + -7.5x + x2 = 11.8125

Factor a perfect square on the left side:
(x + -3.75)(x + -3.75) = 11.8125

Calculate the square root of the right side: 3.436931771

Break this problem into two subproblems by setting 
(x + -3.75) equal to 3.436931771 and -3.436931771.

Subproblem 1

x + -3.75 = 3.436931771 Simplifying x + -3.75 = 3.436931771 Reorder the terms: -3.75 + x = 3.436931771 Solving -3.75 + x = 3.436931771 Solving for variable 'x'. Move all terms containing x to the left, all other terms to the right. Add '3.75' to each side of the equation. -3.75 + 3.75 + x = 3.436931771 + 3.75 Combine like terms: -3.75 + 3.75 = 0.00 0.00 + x = 3.436931771 + 3.75 x = 3.436931771 + 3.75 Combine like terms: 3.436931771 + 3.75 = 7.186931771 x = 7.186931771 Simplifying x = 7.186931771

Subproblem 2

x + -3.75 = -3.436931771 Simplifying x + -3.75 = -3.436931771 Reorder the terms: -3.75 + x = -3.436931771 Solving -3.75 + x = -3.436931771 Solving for variable 'x'. Move all terms containing x to the left, all other terms to the right. Add '3.75' to each side of the equation. -3.75 + 3.75 + x = -3.436931771 + 3.75 Combine like terms: -3.75 + 3.75 = 0.00 0.00 + x = -3.436931771 + 3.75 x = -3.436931771 + 3.75 Combine like terms: -3.436931771 + 3.75 = 0.313068229 x = 0.313068229 Simplifying x = 0.313068229

Solution

The solution to the problem is based on the solutions from the subproblems. x = {7.186931771, 0.313068229}

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