
William W. answered 04/11/22
Experienced Tutor and Retired Engineer
This is not a hard problem, just a tedious problem.
Here is a sketch of L5
You divide the space between 1 and 4 into 5 even increments, so each would be (4 - 1)/5 = 0.6 wide.
You find the function values at the left side of each rectangle (the height of each rectangle) and multiply them by the width (0.6):
f(1)•0.6 + f(1.6)•0.6 + f(2.2)•0.6 + f(2.8)•0.6 + f(3.4)•0.6
Then repeat for the midpoint to get M5:
f(1.3)•0.6 + f(1.9)•0.6 + f(2.5)•0.6 + f(3.1)•0.6 + f(3.7)•0.6
Then repeat for the right side to get R5:
f(1.6)•0.6 + f(2.3)•0.6 + f(2.8)•0.6 + f(3.4)•0.6 + f(4)•0.6
You can use your TI-84 to do this by putting the function in your Y1 and then using the function value "button" however, the easiest way is to use Excel.

William W.
If you need help with Excel, let me know.04/11/22