# Homework Help: Integrating Subtraction?

1. Sep 23, 2014

### mshiddensecret

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. Sep 23, 2014

### Simon Bridge

$$\int_a^b 5f(x)-3\; dx = 5\int_a^b f(x)\; dx - 3\int_a^b\;dx$$

3. Sep 23, 2014

### 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.

4. Sep 23, 2014

### 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