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Evaluate the upper and lower sums for
f(x) = 2 + sin x, 0 ≤ x ≤ , with n = 8.

1 Answer

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Okay, let's evaluate the upper and lower sums for this function with n = 8 intervals:

1) Find the interval size: = /n = /8 =

2) Evaluate the function at the endpoints of 8 intervals:

f(0) = 2 + sin(0) = 2

f() = 2 + sin() = 3

f(/8) = 2 + sin(/8)

f(2/8) = 2 + sin(2/8)

f(3/8) = 2 + sin(3/8)

f(4/8) = 2 + sin(4/8)

f(5/8) = 2 + sin(5/8)

f(6/8) = 2 + sin(6/8)

f(7/8) = 2 + sin(7/8)

3) Upper sum:

U = 2 + (2 + 3)/2 + (2 + 2 + sin(2/8))/2 + (2 + 2 + sin(3/8) + sin(4/8))/2 + (2 + 2 + sin(5/8) + sin(6/8) + sin(7/8))/2

= 14 + 1.79 + 2.5 + 3 + 3.5 = 24.79

4) Lower sum:

L = 2 + (2 + 2)/2 + (2 + 2 + 2)/2 + (2 + 2 + 2 + 2)/2 + (2 + 2 + 2 + 2 + 3)/2

= 14 + 2 + 2 + 2 + 4 = 24

So the upper sum is 24.79 and the lower sum is 24.

Let me know if you need more details!

User James Irwin
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