x^2-21x+45=0

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Solution for x^2-21x+45=0 equation:


Simplifying
x2 + -21x + 45 = 0

Reorder the terms:
45 + -21x + x2 = 0

Solving
45 + -21x + x2 = 0

Solving for variable 'x'.

Begin completing the square.

Move the constant term to the right:

Add '-45' to each side of the equation.
45 + -21x + -45 + x2 = 0 + -45

Reorder the terms:
45 + -45 + -21x + x2 = 0 + -45

Combine like terms: 45 + -45 = 0
0 + -21x + x2 = 0 + -45
-21x + x2 = 0 + -45

Combine like terms: 0 + -45 = -45
-21x + x2 = -45

The x term is -21x.  Take half its coefficient (-10.5).
Square it (110.25) and add it to both sides.

Add '110.25' to each side of the equation.
-21x + 110.25 + x2 = -45 + 110.25

Reorder the terms:
110.25 + -21x + x2 = -45 + 110.25

Combine like terms: -45 + 110.25 = 65.25
110.25 + -21x + x2 = 65.25

Factor a perfect square on the left side:
(x + -10.5)(x + -10.5) = 65.25

Calculate the square root of the right side: 8.077747211

Break this problem into two subproblems by setting 
(x + -10.5) equal to 8.077747211 and -8.077747211.

Subproblem 1

x + -10.5 = 8.077747211 Simplifying x + -10.5 = 8.077747211 Reorder the terms: -10.5 + x = 8.077747211 Solving -10.5 + x = 8.077747211 Solving for variable 'x'. Move all terms containing x to the left, all other terms to the right. Add '10.5' to each side of the equation. -10.5 + 10.5 + x = 8.077747211 + 10.5 Combine like terms: -10.5 + 10.5 = 0.0 0.0 + x = 8.077747211 + 10.5 x = 8.077747211 + 10.5 Combine like terms: 8.077747211 + 10.5 = 18.577747211 x = 18.577747211 Simplifying x = 18.577747211

Subproblem 2

x + -10.5 = -8.077747211 Simplifying x + -10.5 = -8.077747211 Reorder the terms: -10.5 + x = -8.077747211 Solving -10.5 + x = -8.077747211 Solving for variable 'x'. Move all terms containing x to the left, all other terms to the right. Add '10.5' to each side of the equation. -10.5 + 10.5 + x = -8.077747211 + 10.5 Combine like terms: -10.5 + 10.5 = 0.0 0.0 + x = -8.077747211 + 10.5 x = -8.077747211 + 10.5 Combine like terms: -8.077747211 + 10.5 = 2.422252789 x = 2.422252789 Simplifying x = 2.422252789

Solution

The solution to the problem is based on the solutions from the subproblems. x = {18.577747211, 2.422252789}

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