In the expansion of (3 + 2x)^4, what is the coefficient of x^2? (2023)

Practice Questions

Q1
In the expansion of (3 + 2x)^4, what is the coefficient of x^2? (2023)
  1. 36
  2. 48
  3. 54
  4. 24

Questions & Step-by-Step Solutions

In the expansion of (3 + 2x)^4, what is the coefficient of x^2? (2023)
  • Step 1: Identify the expression to expand, which is (3 + 2x)^4.
  • Step 2: Recognize that we need to find the coefficient of x^2 in the 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 = 3, b = 2x, and n = 4.
  • Step 5: We want the term where x has the power of 2, which means we need k = 2 (since b = 2x).
  • Step 6: Calculate C(4, 2), which is the number of ways to choose 2 from 4. C(4, 2) = 4! / (2! * (4-2)!) = 6.
  • Step 7: Calculate (3)^(4-2) = (3)^2 = 9.
  • Step 8: Calculate (2)^(2) = (2)^2 = 4.
  • Step 9: Multiply these values together: Coefficient = C(4, 2) * (3)^2 * (2)^2 = 6 * 9 * 4.
  • Step 10: Perform the multiplication: 6 * 9 = 54, then 54 * 4 = 216.
  • Step 11: Conclude that the coefficient of x^2 in the expansion of (3 + 2x)^4 is 216.
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