Let f be the function defined by f(x)=3ln(x). If three subintervals of equal length are used, what is the value of the left Riemann sum approximation for ∫1103ln(x)dx ? Round to the nearest thousandth if necessary.Answer:
Q. Let f be the function defined by f(x)=3ln(x). If three subintervals of equal length are used, what is the value of the left Riemann sum approximation for ∫1103ln(x)dx ? Round to the nearest thousandth if necessary.Answer:
Calculate Width of Subintervals: To calculate the left Riemann sum, we first need to determine the width of each subinterval. The interval [1,10] has a length of 10−1=9. Since we are using three subintervals of equal length, each subinterval will have a width of 39=3.
Find X-Values for Left Riemann Sum: Next, we need to find the x-values at which we will evaluate the function f(x)=3ln(x) for the left Riemann sum. These x-values are the left endpoints of each subinterval. The first subinterval is [1,4], the second is [4,7], and the third is [7,10]. Therefore, the x-values are 1, 4, and 7.
Evaluate Function at X-Values: Now we evaluate the function f(x) at each of these x-values. f(1)=3ln(1)=0, f(4)=3ln(4), and f(7)=3ln(7).
Calculate Left Riemann Sum: We can now calculate the left Riemann sum by multiplying each function value by the width of the subintervals and summing them up. The left Riemann sum is (f(1)×3)+(f(4)×3)+(f(7)×3).
Substitute Function Values: Substitute the function values into the sum to get the approximation: 0×3 + 3ln(4)×3 + 3ln(7)×3.
Perform Multiplication: Perform the multiplication: 0+(3×3×ln(4))+(3×3×ln(7)).
Calculate Numerical Values: Calculate the numerical values: 0+(9×ln(4))+(9×ln(7)).
Calculate Approximation: Using a calculator, we find that ln(4)≈1.386 and ln(7)≈1.946. So the approximation becomes 0+(9×1.386)+(9×1.946).
Perform Final Calculations: Now we perform the calculations: 0+(9×1.386)+(9×1.946)=0+12.474+17.514.
Round to Nearest Thousandth: Adding these values together gives us the left Riemann sum approximation: 12.474+17.514=29.988.
Round to Nearest Thousandth: Adding these values together gives us the left Riemann sum approximation: 12.474+17.514=29.988. Round to the nearest thousandth if necessary. The approximation is already at the thousandth place, so rounding is not needed. The final answer is 29.988.
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