What is the coefficient of x^4 in the expansion of (3x - 2)^5? (2021)

Practice Questions

Q1
What is the coefficient of x^4 in the expansion of (3x - 2)^5? (2021)
  1. 90
  2. 120
  3. 150
  4. 180

Questions & Step-by-Step Solutions

What is the coefficient of x^4 in the expansion of (3x - 2)^5? (2021)
  • Step 1: Identify the expression to expand, which is (3x - 2)^5.
  • Step 2: Use the Binomial Theorem, which states that (a + b)^n = Σ (nCk * a^(n-k) * b^k) for k = 0 to n.
  • Step 3: In our case, a = 3x, b = -2, and n = 5.
  • Step 4: We want the coefficient of x^4, which means we need the term where (3x) is raised to the power of 4.
  • Step 5: This occurs when k = 1 because (3x)^(5-k) = (3x)^4 when k = 1.
  • Step 6: Calculate nCk, which is 5C1. This equals 5.
  • Step 7: Calculate (3)^4, which is 81.
  • Step 8: Calculate (-2)^1, which is -2.
  • Step 9: Multiply these values together: 5 * 81 * (-2).
  • Step 10: The result is -810, which is the coefficient of x^4.
No concepts available.
Soulshift Feedback ×

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

Not likely Very likely