a^2+18a-13=0

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Solution for a^2+18a-13=0 equation:


Simplifying
a2 + 18a + -13 = 0

Reorder the terms:
-13 + 18a + a2 = 0

Solving
-13 + 18a + a2 = 0

Solving for variable 'a'.

Begin completing the square.

Move the constant term to the right:

Add '13' to each side of the equation.
-13 + 18a + 13 + a2 = 0 + 13

Reorder the terms:
-13 + 13 + 18a + a2 = 0 + 13

Combine like terms: -13 + 13 = 0
0 + 18a + a2 = 0 + 13
18a + a2 = 0 + 13

Combine like terms: 0 + 13 = 13
18a + a2 = 13

The a term is 18a.  Take half its coefficient (9).
Square it (81) and add it to both sides.

Add '81' to each side of the equation.
18a + 81 + a2 = 13 + 81

Reorder the terms:
81 + 18a + a2 = 13 + 81

Combine like terms: 13 + 81 = 94
81 + 18a + a2 = 94

Factor a perfect square on the left side:
(a + 9)(a + 9) = 94

Calculate the square root of the right side: 9.695359715

Break this problem into two subproblems by setting 
(a + 9) equal to 9.695359715 and -9.695359715.

Subproblem 1

a + 9 = 9.695359715 Simplifying a + 9 = 9.695359715 Reorder the terms: 9 + a = 9.695359715 Solving 9 + a = 9.695359715 Solving for variable 'a'. Move all terms containing a to the left, all other terms to the right. Add '-9' to each side of the equation. 9 + -9 + a = 9.695359715 + -9 Combine like terms: 9 + -9 = 0 0 + a = 9.695359715 + -9 a = 9.695359715 + -9 Combine like terms: 9.695359715 + -9 = 0.695359715 a = 0.695359715 Simplifying a = 0.695359715

Subproblem 2

a + 9 = -9.695359715 Simplifying a + 9 = -9.695359715 Reorder the terms: 9 + a = -9.695359715 Solving 9 + a = -9.695359715 Solving for variable 'a'. Move all terms containing a to the left, all other terms to the right. Add '-9' to each side of the equation. 9 + -9 + a = -9.695359715 + -9 Combine like terms: 9 + -9 = 0 0 + a = -9.695359715 + -9 a = -9.695359715 + -9 Combine like terms: -9.695359715 + -9 = -18.695359715 a = -18.695359715 Simplifying a = -18.695359715

Solution

The solution to the problem is based on the solutions from the subproblems. a = {0.695359715, -18.695359715}

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