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Advanced Math / Nonlinear equations in one variable and systems of equations in two variables Difficulty: Medium

55 x + 6 = x

What is the positive solution to the given equation?

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Explanation

The correct answer is 5 . Multiplying both sides of the given equation by x + 6 results in 55=xx+6. Applying the distributive property of multiplication to the right-hand side of this equation results in 55 = x 2 + 6 x . Subtracting 55 from both sides of this equation results in 0 = x 2 + 6 x - 55 . The right-hand side of this equation can be rewritten by factoring. The two values that multiply to -55 and add to 6 are 11 and -5 . It follows that the equation 0 = x 2 + 6 x - 55 can be rewritten as 0=x+11x-5. Setting each factor equal to 0 yields two equations: x + 11 = 0 and x - 5 = 0 . Subtracting 11 from both sides of the equation x + 11 = 0 results in x = -11 . Adding 5 to both sides of the equation x - 5 = 0 results in x = 5 . Therefore, the positive solution to the given equation is 5 .