# Homework Help: Diff EQ Intro - Verify Family of Functions as Solution

1. Aug 27, 2010

### jgiarrusso

1. The problem statement, all variables and given/known data
Verify that the indicated family of functions is a solution of the given differential equation. Assume an appropriate interval I of definition for each solution.

2. Relevant equations
dy/dx + 2xy = 1; y = e-x2$$\int$$(from 0 to x)et2dt + c1e-x2

3. The attempt at a solution
I have only had one class period in differential so far and we didn't get to go over much material. I imagine that one would need to differentiate y(x) with respect to x and plug into the first equation. However, I'm not quite sure what to do with the integral with respect to t. I tried to integrate it, and got et2/(2t), but evaluating that at 0 would cause an implosion. If I differentiate with respect to x, I don't think I can just treat it as a constant because it's evaluated from 0 to x. Could I please get a nudge in the right direction?

2. Aug 27, 2010

This is just simple application of Fundamental Theorem of Calculus.

If $$F(x) = \int_a^x f(t) dt$$ then $$F'(x) = f(x),$$ given of course that f(x) is continuous on [a, x].

3. Aug 28, 2010

### jgiarrusso

So then dy/dx would be:

dy/dx = e-x2 * ex2 - 2xe-x2$$\int$$(from 0 to x)et2dt - 2xc1e-x2

And then plugging it into the differential equation, it all cancels out. Thank you so much!