7x^2=15x-21

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Solution for 7x^2=15x-21 equation:


Simplifying
7x2 = 15x + -21

Reorder the terms:
7x2 = -21 + 15x

Solving
7x2 = -21 + 15x

Solving for variable 'x'.

Reorder the terms:
21 + -15x + 7x2 = -21 + 15x + 21 + -15x

Reorder the terms:
21 + -15x + 7x2 = -21 + 21 + 15x + -15x

Combine like terms: -21 + 21 = 0
21 + -15x + 7x2 = 0 + 15x + -15x
21 + -15x + 7x2 = 15x + -15x

Combine like terms: 15x + -15x = 0
21 + -15x + 7x2 = 0

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

Divide each side by '7'.
3 + -2.142857143x + x2 = 0

Move the constant term to the right:

Add '-3' to each side of the equation.
3 + -2.142857143x + -3 + x2 = 0 + -3

Reorder the terms:
3 + -3 + -2.142857143x + x2 = 0 + -3

Combine like terms: 3 + -3 = 0
0 + -2.142857143x + x2 = 0 + -3
-2.142857143x + x2 = 0 + -3

Combine like terms: 0 + -3 = -3
-2.142857143x + x2 = -3

The x term is -2.142857143x.  Take half its coefficient (-1.071428572).
Square it (1.147959185) and add it to both sides.

Add '1.147959185' to each side of the equation.
-2.142857143x + 1.147959185 + x2 = -3 + 1.147959185

Reorder the terms:
1.147959185 + -2.142857143x + x2 = -3 + 1.147959185

Combine like terms: -3 + 1.147959185 = -1.852040815
1.147959185 + -2.142857143x + x2 = -1.852040815

Factor a perfect square on the left side:
(x + -1.071428572)(x + -1.071428572) = -1.852040815

Can't calculate square root of the right side.

The solution to this equation could not be determined.

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