What is the coefficient of x^2 in the expansion of (3x - 4)^6?

Practice Questions

Q1
What is the coefficient of x^2 in the expansion of (3x - 4)^6?
  1. 540
  2. 720
  3. 1080
  4. 1440

Questions & Step-by-Step Solutions

What is the coefficient of x^2 in the expansion of (3x - 4)^6?
  • Step 1: Identify the expression to expand, which is (3x - 4)^6.
  • 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 = Σ [C(n, k) * a^(n-k) * b^k] for k = 0 to n.
  • Step 4: In our case, a = 3x, b = -4, and n = 6.
  • Step 5: We want the term where the power of x is 2, which means we need to find the term where (3x) is raised to the power of 2.
  • Step 6: This corresponds to k = 6 - 2 = 4, since we want the x^2 term.
  • Step 7: Calculate C(6, 2), which is the number of ways to choose 2 from 6. C(6, 2) = 6! / (2!(6-2)!) = 15.
  • Step 8: Calculate (3)^2, which is 9.
  • Step 9: Calculate (-4)^(6-2), which is (-4)^4. This equals 256.
  • Step 10: Multiply these values together: 15 (from C(6, 2)) * 9 (from (3)^2) * 256 (from (-4)^4).
  • Step 11: Perform the multiplication: 15 * 9 = 135, and then 135 * 256 = 34560.
  • Step 12: The coefficient of x^2 in the expansion of (3x - 4)^6 is 34560.
No concepts available.
Soulshift Feedback ×

On a scale of 0–10, how likely are you to recommend The Soulshift Academy?

Not likely Very likely