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Multiple Choice
Express the following limit as a definite integral on the interval [0,10]. limn→∞∑k=1n(xk∗−3)2Δx
A
∫100(x−3)2dx
B
∫010(x−3)2dx
C
∫0∞(x−3)2dx
D
∫∞0(x−3)2dx
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Verified step by step guidance
1
Recognize that the given limit represents a Riemann sum, which is a method for approximating the value of a definite integral. The general form of a Riemann sum is: limn→∞∑k=1nf(xk∗)Δx, where Δx is the width of each subinterval and xk∗ is a sample point in the k-th subinterval.
Identify the components of the Riemann sum in the problem: f(xk∗) = (xk∗−3)^2 and Δx is the width of each subinterval. The interval of integration is [0, 10], so Δx = (10−0)/n = 10/n.
Understand that xk∗ represents the sample points in the interval [0, 10]. For a uniform partition, xk∗ can be expressed as xk∗ = 0 + kΔx = k(10/n).
Substitute the expressions for xk∗ and Δx into the Riemann sum: limn→∞∑k=1n((k(10/n)−3)^2)(10/n). This represents the Riemann sum for the function f(x) = (x−3)^2 over the interval [0, 10].
Conclude that the limit of the Riemann sum as n→∞ is the definite integral of f(x) = (x−3)^2 over [0, 10]. Therefore, the integral is ∫_0^10 (x−3)^2 dx.