What is the value of the coefficient of x^0 in the expansion of (x + 5)^3?

Practice Questions

Q1
What is the value of the coefficient of x^0 in the expansion of (x + 5)^3?
  1. 0
  2. 5
  3. 15
  4. 125

Questions & Step-by-Step Solutions

What is the value of the coefficient of x^0 in the expansion of (x + 5)^3?
  • Step 1: Understand that x^0 means we are looking for the constant term in the expansion.
  • Step 2: Recognize that (x + 5)^3 is a binomial expression that can be expanded using the binomial theorem.
  • Step 3: The binomial theorem 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 = x, b = 5, and n = 3.
  • Step 5: To find the coefficient of x^0, we need the term where x is raised to the power of 0. This happens when k = 3 (since 3 - k = 0).
  • Step 6: Calculate the coefficient using the formula: nCk * b^k, where n = 3, k = 3, and b = 5.
  • Step 7: Calculate 3C3, which is 1 (there's only one way to choose all 3 items).
  • Step 8: Calculate 5^3, which is 125.
  • Step 9: Multiply the results from Step 7 and Step 8: 1 * 125 = 125.
  • Step 10: Conclude that the coefficient of x^0 in the expansion of (x + 5)^3 is 125.
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