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Homework Help: Integrating Subtraction?

  1. Sep 23, 2014 #1
    Let [PLAIN][PLAIN]http://msr02.math.mcgill.ca/webwork2_files/jsMath/fonts/cmex10/alpha/144/char5A.png [Broken] [Broken] [Broken]f(x)dx=5 a=7, b= 13[PLAIN]http://msr02.math.mcgill.ca/webwork2_files/jsMath/fonts/cmmi10/alpha/144/char3B.png [Broken] [Broken] [PLAIN][PLAIN]http://msr02.math.mcgill.ca/webwork2_files/jsMath/fonts/cmex10/alpha/144/char5A.png [Broken] [Broken] [Broken]f(x)dx=3 a=7, b=9[PLAIN]http://msr02.math.mcgill.ca/webwork2_files/jsMath/fonts/cmmi10/alpha/144/char3B.png [Broken] [Broken] [PLAIN][PLAIN]http://msr02.math.mcgill.ca/webwork2_files/jsMath/fonts/cmex10/alpha/144/char5A.png [Broken] [Broken] [Broken]f(x)dx=5 a=11,b=13

    Find [PLAIN][PLAIN]http://msr02.math.mcgill.ca/webwork2_files/jsMath/fonts/cmex10/alpha/144/char5A.png [Broken] [Broken] [Broken]f(x)dx[FONT=.LucidaGrandeUI]= a=9 b = 11 ==== I figureed out it will be 3+5-5=3 therefore it is =-3[/FONT]
    and [PLAIN][PLAIN]http://msr02.math.mcgill.ca/webwork2_files/jsMath/fonts/cmex10/alpha/144/char5A.png [Broken] [Broken] [Broken](5f(x)−3)dx= a=11 b = 9 I am lost. I know it will be 3 but then its 5f(x)-3 which I don't get.

    a=bottom b=top boundaries
    Last edited by a moderator: May 7, 2017
  2. jcsd
  3. Sep 23, 2014 #2

    Simon Bridge

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    $$\int_a^b 5f(x)-3\; dx = 5\int_a^b f(x)\; dx - 3\int_a^b\;dx$$
  4. Sep 23, 2014 #3


    Staff: Mentor

    Homework-type problems should be posted in the homework & coursework sections, not in the technical math sections. I have moved this thread to the appropriate forum section.
  5. Sep 23, 2014 #4


    Staff: Mentor

    Your problem statement and work are just about incomprehensible. My best guess is that this is the problem statement.
    $$\int_7^{13}f(x)dx = 5 $$
    $$\int_7^{9}f(x)dx = 3 $$
    $$\int_{11}^{13}f(x)dx = 5 $$
    To answer the stated questions, use the rule that says
    $$\int_a^b f(x)dx + \int_b^c f(x)dx = \int_a^c f(x)dx$$
    Last edited by a moderator: May 7, 2017
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