Yahoo Answers is shutting down on May 4th, 2021 (Eastern Time) and beginning April 20th, 2021 (Eastern Time) the Yahoo Answers website will be in read-only mode. There will be no changes to other Yahoo properties or services, or your Yahoo account. You can find more information about the Yahoo Answers shutdown and how to download your data on this help page.

? asked in Science & MathematicsMathematics · 7 years ago

calculus 2 question Differential Equation?

A) dx/dy = e^(5 x)/(3 y^2) and y(0)=3

y(x)=?

Can someone please help I really dont understand :/ can you please include the steps too i will choose best answer so you can get 10 pts

Also:

b) find the solution of the differential equation dx/dy = y^2+9 that satisfies the initial condition y(7)=0

y(x)=?

thanks !

1 Answer

Relevance
  • 7 years ago
    Favorite Answer

    You must've mean dy/dx? Not dx/dy?

    A.)

    dy/dx = e^(5x)/(3y^2)

    Separating variables:

    3y^2 dy = e^(5x) dx

    Integrating both sides:

    y^3 = 1/5*e^(5x) + C

    Plugging in initial condition:

    3^3 = 1/5 + C

    C = 27 - 1/5 = 134/5

    So y = (1/5*e^(5x) + 134/5)^(1/3)

    B.)

    dy/dx = y^2 + 9

    dy/(y^2 + 9) = dx

    Integrating both sides:

    1/3*arctan(y/3) = x + C

    Plugging in initial condition:

    1/3*arctan(0/3) = 7 + C => C = -7

    y/3 = tan(3x - 21)

    y = 3*tan(3x - 21)

Still have questions? Get your answers by asking now.