1. Not finding help here? Sign up for a free 30min 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!

Simple integration for an area problem

  1. Feb 1, 2017 #1
    1. The problem statement, all variables and given/known data

    2. Relevant equations
    Integration of graph is the area.

    3. The attempt at a solution
    I don't think my way should have any problem in it, but I can't get the right answer.
    Are there any careless mistakes in it? Or any other problems?
    And how is the true answer get? And what is the answer?
    Thank you very much
    Last edited: Feb 1, 2017
  2. jcsd
  3. Feb 1, 2017 #2


    Staff: Mentor

    Problems involving integration should NOT be posted in the Precalc section.
    Thread moved.
  4. Feb 1, 2017 #3

    Ray Vickson

    User Avatar
    Science Advisor
    Homework Helper

    I refuse to lie sideways to read your work. Anyway, the preferred method in this forum is for you to type out your solution; some people will look at photos of solutions, but only if they are properly oriented.
  5. Feb 1, 2017 #4
  6. Feb 1, 2017 #5

    Ray Vickson

    User Avatar
    Science Advisor
    Homework Helper

    Your total area result is correct. Computing A2 instead of A1 seems easier, since you do not need to break up the integration region into two parts: you just have ##A_2 = \int_0^{x_m} (4x - 5 x^2 - mx) \, dx,## where ##x_m## is the positive intersection point. From the requirement ##A_2 = (1/2) A## I get the equation
    $$ -\frac{1}{150} m^3+ \frac{2}{25} m^2-\frac{8}{25} m+ \frac{32}{75} = \frac{16}{75},$$
    leading to a much different ##m## than yours.
    Last edited: Feb 1, 2017
  7. Feb 1, 2017 #6


    User Avatar
    Staff Emeritus
    Science Advisor
    Homework Helper
    Gold Member

Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?
Draft saved Draft deleted

Similar Discussions: Simple integration for an area problem