5x^2-30x=-21

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Solution for 5x^2-30x=-21 equation:


Simplifying
5x2 + -30x = -21

Reorder the terms:
-30x + 5x2 = -21

Solving
-30x + 5x2 = -21

Solving for variable 'x'.

Reorder the terms:
21 + -30x + 5x2 = -21 + 21

Combine like terms: -21 + 21 = 0
21 + -30x + 5x2 = 0

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

Divide each side by '5'.
4.2 + -6x + x2 = 0

Move the constant term to the right:

Add '-4.2' to each side of the equation.
4.2 + -6x + -4.2 + x2 = 0 + -4.2

Reorder the terms:
4.2 + -4.2 + -6x + x2 = 0 + -4.2

Combine like terms: 4.2 + -4.2 = 0.0
0.0 + -6x + x2 = 0 + -4.2
-6x + x2 = 0 + -4.2

Combine like terms: 0 + -4.2 = -4.2
-6x + x2 = -4.2

The x term is -6x.  Take half its coefficient (-3).
Square it (9) and add it to both sides.

Add '9' to each side of the equation.
-6x + 9 + x2 = -4.2 + 9

Reorder the terms:
9 + -6x + x2 = -4.2 + 9

Combine like terms: -4.2 + 9 = 4.8
9 + -6x + x2 = 4.8

Factor a perfect square on the left side:
(x + -3)(x + -3) = 4.8

Calculate the square root of the right side: 2.19089023

Break this problem into two subproblems by setting 
(x + -3) equal to 2.19089023 and -2.19089023.

Subproblem 1

x + -3 = 2.19089023 Simplifying x + -3 = 2.19089023 Reorder the terms: -3 + x = 2.19089023 Solving -3 + x = 2.19089023 Solving for variable 'x'. Move all terms containing x to the left, all other terms to the right. Add '3' to each side of the equation. -3 + 3 + x = 2.19089023 + 3 Combine like terms: -3 + 3 = 0 0 + x = 2.19089023 + 3 x = 2.19089023 + 3 Combine like terms: 2.19089023 + 3 = 5.19089023 x = 5.19089023 Simplifying x = 5.19089023

Subproblem 2

x + -3 = -2.19089023 Simplifying x + -3 = -2.19089023 Reorder the terms: -3 + x = -2.19089023 Solving -3 + x = -2.19089023 Solving for variable 'x'. Move all terms containing x to the left, all other terms to the right. Add '3' to each side of the equation. -3 + 3 + x = -2.19089023 + 3 Combine like terms: -3 + 3 = 0 0 + x = -2.19089023 + 3 x = -2.19089023 + 3 Combine like terms: -2.19089023 + 3 = 0.80910977 x = 0.80910977 Simplifying x = 0.80910977

Solution

The solution to the problem is based on the solutions from the subproblems. x = {5.19089023, 0.80910977}

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