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2018 Math Kangaroo

Problem 22

Problem 22 · 2018 Math Kangaroo Stretch
Algebra & Patterns substitution

\(m\) and \(n\) are the solutions of the equation \(x^2 - x - 2018 = 0\). What is the value of the expression \(n^2 + m\)?

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Answer: D — 2019
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Hint 1 of 2
Use the relations between the roots and the equation they satisfy.
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Hint 2 of 2
Replace n² using the original equation.
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Approach: Vieta plus substituting the equation a root satisfies
  1. From x²−x−2018 = 0, the roots satisfy m+n = 1.
  2. Since n is a root, n² = n + 2018.
  3. Then n² + m = (n + 2018) + m = (m+n) + 2018 = 1 + 2018 = 2019.
  4. Answer: 2019.
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