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Mathematics 18 Online
OpenStudy (anonymous):

solve the initial value problem

OpenStudy (anonymous):

\[y \prime =\frac{ x^2+3x+2 }{ y-2 }\] \[y(1)=4\]

OpenStudy (anonymous):

Soooo..... I separated the variables \[y \prime (y-2)=x^2+3x\]

OpenStudy (anonymous):

+2*

OpenStudy (anonymous):

and then I went to integrate them... which got me here \[\frac{ -y^2 }{ 2 }-2y+c=\frac{ x^3 }{ 3 }+\frac{ 3x^2 }{ 2 }+2x\]

OpenStudy (anonymous):

but I feel like I am wrong

OpenStudy (turingtest):

it looks fine to me, but the actual "separation of hte variables" is a step that you skipped. you should have written \[y'(y-2)=x^2+3x+2\\\frac{dy}{dx}(y-2)=x^2+3x+2\\(y-2)dy=(x^2+3x+2)dx\\integrate...\]

OpenStudy (turingtest):

the separation of the variables is the part where you move the dx and dy on different sides, not the variables themselves your answer is correct though, except for the +C from the constant

OpenStudy (anonymous):

Ooooh. Okay well what do you mean about the +c? Does it go on both sides? Lol I just always add it in

OpenStudy (turingtest):

well it technically goes on both sides so you would get \[f(y)+C_1=f(x)+C_2\]but since they are constants we can just say\[f(y)=f(x)+(C_2-C_1)=f(x)+C_3\] since subtracting or adding two constants we don't know the value of just makes nother constant we also don't know the value of

OpenStudy (turingtest):

but you *always* get a +C when you do an indefinite integral

OpenStudy (anonymous):

So, when I solve for the initial value problem I'm solving for say C3 on the right hand side?

OpenStudy (turingtest):

correct :)

OpenStudy (anonymous):

okay, thank you :)

OpenStudy (turingtest):

welcome!

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