x^2+15x+51=0

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Solution for x^2+15x+51=0 equation:


Simplifying
x2 + 15x + 51 = 0

Reorder the terms:
51 + 15x + x2 = 0

Solving
51 + 15x + x2 = 0

Solving for variable 'x'.

Begin completing the square.

Move the constant term to the right:

Add '-51' to each side of the equation.
51 + 15x + -51 + x2 = 0 + -51

Reorder the terms:
51 + -51 + 15x + x2 = 0 + -51

Combine like terms: 51 + -51 = 0
0 + 15x + x2 = 0 + -51
15x + x2 = 0 + -51

Combine like terms: 0 + -51 = -51
15x + x2 = -51

The x term is 15x.  Take half its coefficient (7.5).
Square it (56.25) and add it to both sides.

Add '56.25' to each side of the equation.
15x + 56.25 + x2 = -51 + 56.25

Reorder the terms:
56.25 + 15x + x2 = -51 + 56.25

Combine like terms: -51 + 56.25 = 5.25
56.25 + 15x + x2 = 5.25

Factor a perfect square on the left side:
(x + 7.5)(x + 7.5) = 5.25

Calculate the square root of the right side: 2.291287847

Break this problem into two subproblems by setting 
(x + 7.5) equal to 2.291287847 and -2.291287847.

Subproblem 1

x + 7.5 = 2.291287847 Simplifying x + 7.5 = 2.291287847 Reorder the terms: 7.5 + x = 2.291287847 Solving 7.5 + x = 2.291287847 Solving for variable 'x'. Move all terms containing x to the left, all other terms to the right. Add '-7.5' to each side of the equation. 7.5 + -7.5 + x = 2.291287847 + -7.5 Combine like terms: 7.5 + -7.5 = 0.0 0.0 + x = 2.291287847 + -7.5 x = 2.291287847 + -7.5 Combine like terms: 2.291287847 + -7.5 = -5.208712153 x = -5.208712153 Simplifying x = -5.208712153

Subproblem 2

x + 7.5 = -2.291287847 Simplifying x + 7.5 = -2.291287847 Reorder the terms: 7.5 + x = -2.291287847 Solving 7.5 + x = -2.291287847 Solving for variable 'x'. Move all terms containing x to the left, all other terms to the right. Add '-7.5' to each side of the equation. 7.5 + -7.5 + x = -2.291287847 + -7.5 Combine like terms: 7.5 + -7.5 = 0.0 0.0 + x = -2.291287847 + -7.5 x = -2.291287847 + -7.5 Combine like terms: -2.291287847 + -7.5 = -9.791287847 x = -9.791287847 Simplifying x = -9.791287847

Solution

The solution to the problem is based on the solutions from the subproblems. x = {-5.208712153, -9.791287847}

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