Verified Solution Mathematics Quadratic Equations

Revised Question 56: If a is a root of the equation x² - x - 1 = 0, then the value of a³ - 2a + 1 is:

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Solution ✔ Verified
  • A0
  • B1
  • C2
  • D-1
Explanation

Since a is a root of x² - x - 1 = 0, we have a² - a - 1 = 0, which implies a² = a + 1. Now substitute this into the expression: a³ - 2a + 1 = a(a²) - 2a + 1 = a(a+1) - 2a + 1 = a² + a - 2a + 1 = a² - a + 1. Since a² - a - 1 = 0, it means a² - a = 1. Therefore, (a² - a) + 1 = 1 + 1 = 2.

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