Trapezoidal rule (1 Viewer)

[mmmm.]

When looking at questions on trapezoidal rule, some questions say using 5 subintervals whereas some say 5 function values, is there a difference between these? Because when finding height (b-a/n) i remember that for subintervals n is 4, whereas for function values n is 5, or am i wrong?

Idk if I've worded my question properly, so let me know if you understand what I'm asking

 

[shashysha]

Don't quite remember trapezoidal rule lol but I think subintervals is the amount of 'spaces' under the curve whereas function values are like actual values. An analogy my teacher gave was think of the function values as sticks and the subintervals as goals. If you have 5 sticks, there would be 4 goals in between, so there'd be 5 function values and 4 subintervals. Hope that makes sense

 

[mmmm.]

So if it asked for 5 subintervals it would be b-a/5 and if it asked for 5 function values it would be b-a/4??

 

[shashysha]

So if it asked for 5 subintervals it would be b-a/5 and if it asked for 5 function values it would be b-a/4??

if i remember correctly then yep that should be right

 

[mmmm.]

yeah, i just looked over the textbook and that is right, thankyou

 

[Drongoski]

If you have 5 function values, you have 4 intervals between them. Understand and don't just memorise formulas.