# Need some diffential equation help

1. Jan 24, 2006

### dm84z28

ok, i am having a bit of trouble with this equation.
The question in the book is i need to find the maximum current(I) in an LR circuit, with L=10 Henry, and the Resistor of 1 ohm, and the time that it occurs. It also states that the emf E is given by E(t) = 5exp(-.05t) with the initial condition that the current (I) at time t=0 is 0
ok , i know that L(dI/dt) + IR = E, and i simplified it down to 10I' + (1/10)I = 5exp(-.05t). i also know that this equation is not separable, so i need to find an integrating factor, but unfortunately, my teacher was very vague about how to find and use the integrating factor.
I know that the integrating factor comes from the first order general equation x'(t) = a(t)x(t)+f(t), and also i know that the integrating factor u is Exp(integral(a(t)dt)). so in this case, am i right to say that the integrating factor is exp(-t)?
finally, i am totally lost when it comes to actually using the integrating factor. any help would be greatly appreciated
EDIT:
never mind, i figured it out!

Last edited: Jan 25, 2006