In the expansion of (x + 2)^5, what is the coefficient of x^4?

Practice Questions

Q1
In the expansion of (x + 2)^5, what is the coefficient of x^4?
  1. 5
  2. 10
  3. 20
  4. 30

Questions & Step-by-Step Solutions

In the expansion of (x + 2)^5, what is the coefficient of x^4?
  • Step 1: Identify the expression to expand, which is (x + 2)^5.
  • Step 2: Recognize that we need to find the coefficient of x^4 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 = 5.
  • Step 5: We want the term where x is raised to the power of 4, which means we need k = 1 (since 5 - 4 = 1).
  • Step 6: Calculate the binomial coefficient C(5, 1), which is the number of ways to choose 1 from 5. This equals 5.
  • Step 7: Calculate 2 raised to the power of 1, which is 2.
  • Step 8: Multiply the results from Step 6 and Step 7: 5 * 2 = 10.
  • Step 9: Conclude that the coefficient of x^4 in the expansion of (x + 2)^5 is 10.
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