# Math Help - find u'(x)

1. ## find u'(x)

so i have the function: Y^'+ P(x)y=Q(x) where u(x) is the integrating factor, find u'(x).

i have an answer i wanted to know if its right? i dont know why but i can attach my pdf file, anyways my answer is u'(x) = P(x)u(x)....is this right? thanks in advance..

2. Originally Posted by slapmaxwell1
so i have the function: Y^'+ P(x)y=Q(x) where u(x) is the integrating factor, find u'(x).

i have an answer i wanted to know if its right? i dont know why but i can attach my pdf file, anyways my answer is u'(x) = P(x)u(x)....is this right? thanks in advance..
When you multiply through by $u(x)$ the left hand side will be the derivative of $u(x)y(x)$, that is:

$\frac{d}{dx}\left[u(x)y(x)\right]$ $= u(x)y'(x)+u'(x)y(x)= u(x)y'(x)+u(u)P(x)y(x)=u(x)Q(x)$

So $u'(x)=P(x)u(x)$

CB

3. awesome i actually did it right! wait til my teacher finds out, im not retarded LOL