In the expansion of (3x - 2)^6, what is the coefficient of x^4? (2022)

Practice Questions

Q1
In the expansion of (3x - 2)^6, what is the coefficient of x^4? (2022)
  1. 540
  2. 810
  3. 729
  4. 486

Questions & Step-by-Step Solutions

In the expansion of (3x - 2)^6, what is the coefficient of x^4? (2022)
  • Step 1: Identify the expression to expand, which is (3x - 2)^6.
  • Step 2: Recognize that we need to find the coefficient of x^4 in the expansion.
  • Step 3: Use the Binomial Theorem, which states that (a + b)^n = Σ (nCk * a^(n-k) * b^k) for k = 0 to n.
  • Step 4: In our case, a = 3x, b = -2, and n = 6.
  • Step 5: We want the term where the power of x is 4, which means we need (3x) raised to the power of 4.
  • Step 6: This means we need to find the term where k = 2 (since 6 - k = 4).
  • Step 7: Calculate the binomial coefficient: 6C2 = 6! / (2!(6-2)!) = 15.
  • Step 8: Calculate (3)^4, which is 81.
  • Step 9: Calculate (-2)^2, which is 4.
  • Step 10: Multiply the results: 15 * 81 * 4 = 4860.
  • Step 11: Conclude that the coefficient of x^4 in the expansion of (3x - 2)^6 is 4860.
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