What is the value of the coefficient of x^2 in the expansion of (3x - 2)^4?

Practice Questions

Q1
What is the value of the coefficient of x^2 in the expansion of (3x - 2)^4?
  1. -36
  2. 36
  3. -54
  4. 54

Questions & Step-by-Step Solutions

What is the value of the coefficient of x^2 in the expansion of (3x - 2)^4?
  • Step 1: Identify the expression to expand, which is (3x - 2)^4.
  • Step 2: Recognize that we need to find the coefficient of x^2 in this expansion.
  • Step 3: Use the binomial theorem, which states that (a + b)^n = sum of (nCk * a^(n-k) * b^k) for k from 0 to n.
  • Step 4: In our case, a = 3x, b = -2, and n = 4.
  • Step 5: We need to find the term where the power of x is 2. This happens when k = 2 because (3x)^(2) will give us x^2.
  • Step 6: Calculate nCk, which is 4C2. This is the number of ways to choose 2 items from 4, which equals 6.
  • Step 7: Calculate (3x)^(2) = (3^2)(x^2) = 9x^2.
  • Step 8: Calculate (-2)^(2) = 4.
  • Step 9: Multiply the results from steps 6, 7, and 8: 6 * 9 * 4.
  • Step 10: Perform the multiplication: 6 * 9 = 54, then 54 * 4 = 216.
  • Step 11: The coefficient of x^2 in the expansion is 216.
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