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chambek
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dy/dx+3y=7 y(0)=0
Find a particular solution to the nonhomogeneous differential equation.
 one year ago
 one year ago
chambek Group Title
dy/dx+3y=7 y(0)=0 Find a particular solution to the nonhomogeneous differential equation.
 one year ago
 one year ago

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chambek Group TitleBest ResponseYou've already chosen the best response.0
Also.....Find the solution to the initial value problem. I'm trying to learn this on my own but really am just not getting it.
 one year ago

UnkleRhaukus Group TitleBest ResponseYou've already chosen the best response.1
\[\frac{\mathrm dy}{\mathrm dx}+3y=7\] is a linear equation of the from \[\frac{\mathrm dy}{\mathrm dx}+p(x)y=q(x)\] to solve the linear equation we need an integrating factor \[\mu(x)=e^{\int p(x)\text dx}\] then \[\frac{\mathrm d}{\mathrm dx}\big(\mu(x)y\big)=\mu(x) q(x)\]\[\mu(x)y=\int{\mu(x) q(x)\text dx} \] \[y=\quad\dots\]
 one year ago

UnkleRhaukus Group TitleBest ResponseYou've already chosen the best response.1
after integration you will have a constant of integration, substituting the initial value will allow you to find it
 one year ago

chambek Group TitleBest ResponseYou've already chosen the best response.0
I got the first part! Thanks, I'm trying to get the part with the initial value now....where do i substitute that in?
 one year ago

UnkleRhaukus Group TitleBest ResponseYou've already chosen the best response.1
y = y(x) the condition is y(0) = 0 which means (x,y) = (0,0) is a solution
 one year ago

chambek Group TitleBest ResponseYou've already chosen the best response.0
ok....doing that I got 0....and that was wrong, it is asking for a y=..... I'm sorry i dont understand my professor at all so i essentially now nothing about diffe q's
 one year ago

chambek Group TitleBest ResponseYou've already chosen the best response.0
or grammar apparently....
 one year ago

UnkleRhaukus Group TitleBest ResponseYou've already chosen the best response.1
can you show some working
 one year ago

chambek Group TitleBest ResponseYou've already chosen the best response.0
sure, so i got (7/3) as the particular solution to the nonhomogeneous equation. then going from there, I included a C in my integral so I could plug in 0 for y and solce for c, then get an equation for y=.... \[3y=7+C\] I found C to be 7 at y(0)=0 giving me \[3y=77\] which just doesnt really make too much sense, but I tried 0 regardless and realized I have no clue what I'm doing haha
 one year ago

chambek Group TitleBest ResponseYou've already chosen the best response.0
oh no wait a second....hold on
 one year ago

chambek Group TitleBest ResponseYou've already chosen the best response.0
grrr nevermind, that still got me 0, I had made a mistake in my algebra......
 one year ago

UnkleRhaukus Group TitleBest ResponseYou've already chosen the best response.1
\[\frac{\mathrm dy}{\mathrm dx}+3y=7\]\[\mu(x)=e^{\int 3\text dx}=e^{3\int \text dx}=e^{3x}\]\[\frac{\mathrm d}{\mathrm dx}\big(e^{3x}y\big)=7e^{3x}\] \[e^{3x}y=\int{7 e^{3x}\text dx}=7\int e^{3x}\text dx=7\frac{e^{3x}}3+c\] \[y=\frac73+ce^{3x}\] \[y(0)=0\] \[0=\frac73+c\]\[c=\frac73\] \[y=\frac73\frac73e^{3x}\]
 one year ago

chambek Group TitleBest ResponseYou've already chosen the best response.0
..............so, i got that awhile ago, and I kept putting the answer in as you have it, but, the equation is in terms of t.......*facepalm* thanks for the help!
 one year ago
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