What is the coefficient of x^2 in the expansion of (x - 2)^5?

Practice Questions

Q1
What is the coefficient of x^2 in the expansion of (x - 2)^5?
  1. -40
  2. -20
  3. 20
  4. 40

Questions & Step-by-Step Solutions

What is the coefficient of x^2 in the expansion of (x - 2)^5?
  • Step 1: Identify the expression to expand, which is (x - 2)^5.
  • Step 2: Use the Binomial Theorem, which states that (a + b)^n = sum of (nCk * a^(n-k) * b^k) for k from 0 to n.
  • Step 3: In our case, a = x, b = -2, and n = 5.
  • Step 4: We want the coefficient of x^2, which corresponds to k = 3 (since n - k = 2).
  • Step 5: Calculate nCk, which is 5C3. This is equal to 5! / (3! * (5-3)!) = 10.
  • Step 6: Calculate (-2)^3, which is -2 * -2 * -2 = -8.
  • Step 7: Multiply the results from Step 5 and Step 6: 10 * (-8) = -80.
  • Step 8: Conclude that the coefficient of x^2 in the expansion of (x - 2)^5 is -80.
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