4x^2=21x-18

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Solution for 4x^2=21x-18 equation:


Simplifying
4x2 = 21x + -18

Reorder the terms:
4x2 = -18 + 21x

Solving
4x2 = -18 + 21x

Solving for variable 'x'.

Reorder the terms:
18 + -21x + 4x2 = -18 + 21x + 18 + -21x

Reorder the terms:
18 + -21x + 4x2 = -18 + 18 + 21x + -21x

Combine like terms: -18 + 18 = 0
18 + -21x + 4x2 = 0 + 21x + -21x
18 + -21x + 4x2 = 21x + -21x

Combine like terms: 21x + -21x = 0
18 + -21x + 4x2 = 0

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

Divide each side by '4'.
4.5 + -5.25x + x2 = 0

Move the constant term to the right:

Add '-4.5' to each side of the equation.
4.5 + -5.25x + -4.5 + x2 = 0 + -4.5

Reorder the terms:
4.5 + -4.5 + -5.25x + x2 = 0 + -4.5

Combine like terms: 4.5 + -4.5 = 0.0
0.0 + -5.25x + x2 = 0 + -4.5
-5.25x + x2 = 0 + -4.5

Combine like terms: 0 + -4.5 = -4.5
-5.25x + x2 = -4.5

The x term is -5.25x.  Take half its coefficient (-2.625).
Square it (6.890625) and add it to both sides.

Add '6.890625' to each side of the equation.
-5.25x + 6.890625 + x2 = -4.5 + 6.890625

Reorder the terms:
6.890625 + -5.25x + x2 = -4.5 + 6.890625

Combine like terms: -4.5 + 6.890625 = 2.390625
6.890625 + -5.25x + x2 = 2.390625

Factor a perfect square on the left side:
(x + -2.625)(x + -2.625) = 2.390625

Calculate the square root of the right side: 1.54616461

Break this problem into two subproblems by setting 
(x + -2.625) equal to 1.54616461 and -1.54616461.

Subproblem 1

x + -2.625 = 1.54616461 Simplifying x + -2.625 = 1.54616461 Reorder the terms: -2.625 + x = 1.54616461 Solving -2.625 + x = 1.54616461 Solving for variable 'x'. Move all terms containing x to the left, all other terms to the right. Add '2.625' to each side of the equation. -2.625 + 2.625 + x = 1.54616461 + 2.625 Combine like terms: -2.625 + 2.625 = 0.000 0.000 + x = 1.54616461 + 2.625 x = 1.54616461 + 2.625 Combine like terms: 1.54616461 + 2.625 = 4.17116461 x = 4.17116461 Simplifying x = 4.17116461

Subproblem 2

x + -2.625 = -1.54616461 Simplifying x + -2.625 = -1.54616461 Reorder the terms: -2.625 + x = -1.54616461 Solving -2.625 + x = -1.54616461 Solving for variable 'x'. Move all terms containing x to the left, all other terms to the right. Add '2.625' to each side of the equation. -2.625 + 2.625 + x = -1.54616461 + 2.625 Combine like terms: -2.625 + 2.625 = 0.000 0.000 + x = -1.54616461 + 2.625 x = -1.54616461 + 2.625 Combine like terms: -1.54616461 + 2.625 = 1.07883539 x = 1.07883539 Simplifying x = 1.07883539

Solution

The solution to the problem is based on the solutions from the subproblems. x = {4.17116461, 1.07883539}

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