Determine the coefficient of x^2 in the expansion of (3x - 4)^4.

Practice Questions

Q1
Determine the coefficient of x^2 in the expansion of (3x - 4)^4.
  1. 144
  2. 216
  3. 108
  4. 96

Questions & Step-by-Step Solutions

Determine the coefficient of x^2 in the expansion of (3x - 4)^4.
Correct Answer: 864
  • Step 1: Identify the expression to expand, which is (3x - 4)^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 = 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 = 4.
  • Step 5: We want the term where the power of x is 2, which means we need (3x)^(2) and (-4)^(4-2).
  • Step 6: Set k = 2, since we want the x^2 term. Calculate C(4, 2), which is the number of ways to choose 2 from 4.
  • Step 7: C(4, 2) = 4! / (2! * (4-2)!) = 6.
  • Step 8: Calculate (3)^2, which is 9.
  • Step 9: Calculate (-4)^2, which is 16.
  • Step 10: Multiply these values together: 6 (from C(4, 2)) * 9 (from (3)^2) * 16 (from (-4)^2).
  • Step 11: Perform the multiplication: 6 * 9 = 54, then 54 * 16 = 864.
  • Step 12: The coefficient of x^2 in the expansion of (3x - 4)^4 is 864.
  • Binomial Expansion – The process of expanding expressions that are raised to a power, using the Binomial Theorem.
  • Coefficients in Polynomial Expansion – Understanding how to find specific coefficients in the expansion of polynomials.
  • Combinatorial Coefficients – Using combinations to determine the number of ways to choose terms from the expansion.
Soulshift Feedback ×

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

Not likely Very likely