What is the coefficient of x^3 in the expansion of (x - 2)^6?

Practice Questions

Q1
What is the coefficient of x^3 in the expansion of (x - 2)^6?
  1. -80
  2. -120
  3. -240
  4. -720

Questions & Step-by-Step Solutions

What is the coefficient of x^3 in the expansion of (x - 2)^6?
  • Step 1: Identify the expression we need to expand, which is (x - 2)^6.
  • Step 2: Use the Binomial Theorem, which states that (a + b)^n = Σ [C(n, k) * a^(n-k) * b^k] for k = 0 to n.
  • Step 3: In our case, a = x, b = -2, and n = 6.
  • Step 4: We want the coefficient of x^3, which means we need to find the term where the power of x is 3.
  • Step 5: To find this term, we set n-k = 3, which means k = 6 - 3 = 3.
  • Step 6: Calculate C(6, 3), which is the number of ways to choose 3 items from 6. This is equal to 6! / (3! * (6-3)!) = 20.
  • Step 7: Now calculate (-2)^3, which is -2 * -2 * -2 = -8.
  • Step 8: Multiply the coefficient C(6, 3) by (-2)^3: 20 * (-8) = -160.
  • Step 9: The coefficient of x^3 in the expansion of (x - 2)^6 is -160.
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