What is the coefficient of x^4 in the expansion of (x + 1)^6?
Practice Questions
Q1
What is the coefficient of x^4 in the expansion of (x + 1)^6?
15
20
30
35
Questions & Step-by-Step Solutions
What is the coefficient of x^4 in the expansion of (x + 1)^6?
Step 1: Understand that we need to find the coefficient of x^4 in the expression (x + 1)^6.
Step 2: Recognize that (x + 1)^6 can be expanded using the Binomial Theorem, which states that (a + b)^n = Σ (C(n, k) * a^(n-k) * b^k) for k = 0 to n.
Step 3: In our case, a = x, b = 1, and n = 6.
Step 4: We want the term where x is raised to the power of 4, which means we need to find the term where k = 2 (since 6 - k = 4).
Step 5: Calculate C(6, 2), which is the number of ways to choose 2 items from 6. This is calculated as C(6, 2) = 6! / (2!(6-2)!) = 6! / (2! * 4!) = (6 * 5) / (2 * 1) = 15.
Step 6: The coefficient of x^4 in the expansion of (x + 1)^6 is therefore 15.
