In the expansion of (x + 2)^8, what is the coefficient of x^6?

Practice Questions

Q1
In the expansion of (x + 2)^8, what is the coefficient of x^6?
  1. 28
  2. 56
  3. 84
  4. 112

Questions & Step-by-Step Solutions

In the expansion of (x + 2)^8, what is the coefficient of x^6?
  • Step 1: Identify the expression we are working with, which is (x + 2)^8.
  • Step 2: Recognize that we want to find the coefficient of x^6 in this expansion.
  • Step 3: 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 4: In our case, a = x, b = 2, and n = 8.
  • Step 5: We need to find the term where x is raised to the power of 6. This means we need k = 2 (since 8 - 6 = 2).
  • Step 6: Calculate C(8, 2), which is the number of ways to choose 2 items from 8. C(8, 2) = 8! / (2!(8-2)!) = 28.
  • Step 7: Calculate (2)^2, which is the value of b raised to the power of k. (2)^2 = 4.
  • Step 8: Multiply the results from Step 6 and Step 7 to find the coefficient: 28 * 4 = 112.
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