1. Limited time only! Sign up for a free 30min personal tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Homework Help: Integral draw a line problem

  1. Jan 22, 2005 #1
    [tex]\int_1^{13} f(x) - \int_1^{10} f(x) = \int_a^{b} f(x)[/tex]


    where a = ____ and b = ____

    what is it asking me extactly? is it just telling me to substract the b's and a's? if so, a = 0 and b = 3, but it's wrong.
  2. jcsd
  3. Jan 22, 2005 #2


    User Avatar
    Science Advisor
    Homework Helper

    Draw f(x) on a graph (it doesn't really matter what f(x) is, just draw a curvy line from 0 to 13). Draw a vertical line from x=1 to the curve. Draw a vertical line from 10 to the curve. Draw a vertical line from 13 to the curve.

    Your first integral is the area under the curve from 1 to 13. The second integral subtracts the area under the curve from 1 to 10 (shade it in). What are you left with. This is the area you want to calculate.

    You're right you have an interval of 3, but unless f(x) is a straight horizontal line, the area from 10 to 13 won't necessarily be the same as the area from 0 to 3.
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook