What is the value of the coefficient of x^4 in the expansion of (2x - 5)^6?

Practice Questions

Q1
What is the value of the coefficient of x^4 in the expansion of (2x - 5)^6?
  1. -600
  2. -720
  3. 720
  4. 600

Questions & Step-by-Step Solutions

What is the value of the coefficient of x^4 in the expansion of (2x - 5)^6?
  • Step 1: Identify the expression we need to expand, which is (2x - 5)^6.
  • Step 2: 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 3: In our case, a = 2x, b = -5, and n = 6.
  • Step 4: We want the coefficient of x^4, which means we need to find the term where (2x) is raised to the power of 4.
  • Step 5: If (2x) is raised to the power of 4, then (-5) must be raised to the power of (6 - 4) = 2.
  • Step 6: The term we are looking for is given by the formula: nCk * (2x)^(n-k) * (-5)^k, where k = 2.
  • Step 7: Calculate nCk, which is 6C2. This is equal to 6! / (2!(6-2)!) = 15.
  • Step 8: Calculate (2)^4, which is 16.
  • Step 9: Calculate (-5)^2, which is 25.
  • Step 10: Multiply these values together: 15 * 16 * 25.
  • Step 11: Calculate 15 * 16 = 240.
  • Step 12: Then calculate 240 * 25 = 600.
  • Step 13: Since the term involves (-5), the coefficient will be negative, so the final coefficient is -600.
No concepts available.
Soulshift Feedback ×

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

Not likely Very likely