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

Practice Questions

Q1
In the expansion of (x + 3)^4, what is the coefficient of x^3? (2023)
  1. 36
  2. 48
  3. 54
  4. 64

Questions & Step-by-Step Solutions

In the expansion of (x + 3)^4, what is the coefficient of x^3? (2023)
  • Step 1: Identify the expression we are expanding, which is (x + 3)^4.
  • Step 2: Recognize that we want to find the coefficient of x^3 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 = 3, and n = 4.
  • Step 5: We need to find the term where x is raised to the power of 3, which means we need k = 1 (since n - k = 3).
  • Step 6: Calculate C(4, 3), which is the number of ways to choose 3 items from 4. This equals 4.
  • Step 7: Calculate (3)^1, which is simply 3.
  • Step 8: Multiply the results from Step 6 and Step 7: 4 * 3 = 12.
  • Step 9: Conclude that the coefficient of x^3 in the expansion of (x + 3)^4 is 12.
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