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Multiple Choice
Which of the following limits is equal to the definite integral from to of ?
A
B
C
D
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Verified step by step guidance
1
Step 1: Recall the definition of a definite integral as the limit of a Riemann sum. The definite integral from a to b of a function f(x) dx can be expressed as lim_{n \(\to\) \(\infty\)} \(\sum\)_{i=1}^n f(x_i) \(\cdot\) \(\Delta\) x, where \(\Delta\) x = \(\frac{b-a}{n}\) and x_i represents the sample points within each subinterval.
Step 2: Identify the interval of integration. In this problem, the definite integral is from 2 to 5, so the interval is [2, 5]. The width of each subinterval is \(\Delta\) x = \(\frac{5-2}{n}\) = \(\frac{3}{n}\).
Step 3: Determine the sample points x_i within the interval. A common choice for sample points is the left endpoint of each subinterval, which can be expressed as x_i = 2 + i \(\cdot\) \(\Delta\) x = 2 + \(\frac{3i}{n}\).
Step 4: Substitute the function f(x) = 1 + x^4 into the Riemann sum formula. The sum becomes \(\sum\)_{i=1}^n \(\left\)[1 + \(\left\)(2 + \(\frac{3i}{n}\)\(\right\))^4\(\right\)] \(\cdot\) \(\Delta\) x, where \(\Delta\) x = \(\frac{3}{n}\).
Step 5: Compare the given options to the derived Riemann sum expression. The correct limit is lim_{n \(\to\) \(\infty\)} \(\sum\)_{i=1}^n \(\left\)[1 + \(\left\)(2 + \(\frac{3i}{n}\)\(\right\))^4\(\right\)] \(\cdot\) \(\frac{3}{n}\), as it matches the interval, sample points, and function provided in the problem.