Let f be the function defined by f(x)=x6. If three subintervals of equal length are used, what is the value of the trapezoidal sum approximation for ∫18.5x6dx ? Round to the nearest thousandth if necessary.Answer:
Q. Let f be the function defined by f(x)=x6. If three subintervals of equal length are used, what is the value of the trapezoidal sum approximation for ∫18.5x6dx ? Round to the nearest thousandth if necessary.Answer:
Determine subinterval width: To use the trapezoidal rule, we first need to determine the width of each subinterval. The interval from 1 to 8.5 has a length of 8.5−1=7.5. Since we are using three subintervals of equal length, each subinterval will have a width of 7.5/3=2.5.
Calculate x-values: Next, we need to calculate the x-values at the endpoints of each subinterval. The first subinterval starts at x=1 and ends at x=1+2.5=3.5. The second subinterval ends at x=3.5+2.5=6. The third subinterval ends at x=6+2.5=8.5. So, the x-values we will use are 1, 3.5, 6, and 8.5.
Evaluate function: Now we need to evaluate the function f(x)=x6 at each of these x-values. This gives us f(1)=16=6, f(3.5)=3.56≈1.714, f(6)=66=1, and f(8.5)=8.56≈0.706.
Calculate trapezoidal sum: The trapezoidal sum is given by the formula (2width)×(f(x0)+2⋅f(x1)+2⋅f(x2)+…+f(xn)), where x0 and xn are the endpoints of the interval and x1 through xn−1 are the points in between. In our case, this becomes (22.5)×(f(1)+2⋅f(3.5)+2⋅f(6)+f(8.5)).
Calculate final value: Plugging in the values we found, the trapezoidal sum is (2.5/2)×(6+2×1.714+2×1+0.706)=(1.25)×(6+3.428+2+0.706)=(1.25)×(12.134)≈15.1675.
Round to nearest thousandth: Rounding to the nearest thousandth, the value of the trapezoidal sum approximation for the integral is approximately 15.168.
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