What is the coefficient of x^2 in the expansion of (x - 4)^6?
Practice Questions
1 question
Q1
What is the coefficient of x^2 in the expansion of (x - 4)^6?
240
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720
Using the binomial theorem, the coefficient of x^2 in (a + b)^n is given by nCk * a^(n-k) * b^k. Here, n=6, a=x, b=-4, and k=2. Thus, the coefficient is 6C2 * (1)^4 * (-4)^2 = 15 * 16 = 240.
Questions & Step-by-step Solutions
1 item
Q
Q: What is the coefficient of x^2 in the expansion of (x - 4)^6?
Solution: Using the binomial theorem, the coefficient of x^2 in (a + b)^n is given by nCk * a^(n-k) * b^k. Here, n=6, a=x, b=-4, and k=2. Thus, the coefficient is 6C2 * (1)^4 * (-4)^2 = 15 * 16 = 240.
Steps: 10
Step 1: Identify the expression we need to expand, which is (x - 4)^6.
Step 2: Recognize that we will use the binomial theorem to find the coefficient of x^2.
Step 3: In the binomial theorem, we have (a + b)^n, where n is the exponent. Here, n = 6, a = x, and b = -4.
Step 4: We need to find the term that contains x^2. This corresponds to k = 2 in the binomial expansion.
Step 5: The formula for the coefficient of x^k in (a + b)^n is given by nCk * a^(n-k) * b^k.
Step 6: Calculate nCk, which is 6C2. This is calculated as 6! / (2! * (6-2)!) = 15.
Step 7: Calculate a^(n-k), which is x^(6-2) = x^4. The coefficient here is 1.
