Mathematics Stack Exchange is a question and answer site for people studying math at any level and professionals in related fields. It's 100% free, no registration required.

Sign up
Here's how it works:
  1. Anybody can ask a question
  2. Anybody can answer
  3. The best answers are voted up and rise to the top

Guess is $y = Ax+B$.

$y''' = 0$

$y' = A$

Thus, the differential equation becomes:

$0 + 8(A) = -8x-3$

Where can I go from here? I can't find an explicit solution for A, and my work doesn't even involve the variable B. Any help?

share|cite|improve this question
Well, you started with a guess and got stuck. Which kind of suggests that a different guess might be a way out.... Hint: You're going to need at least some $x$-term on the left-hand side, so maybe a polynomial with degree $\geq 2$ wouldn't be a bad idea. – fgp Oct 20 '12 at 0:49
up vote 2 down vote accepted

You'll need $y_p = (Ax+B)x = Ax^2 + Bx$, since the characteristic eqn. of your ODE has $0$ as a root.

$$y'_p = 2Ax + B$$

$$y'''_p = 0$$

So we have:

$$0 + 8(2Ax + B) = -8x - 3$$

And you should be able to take it from there.

share|cite|improve this answer

Your Answer


By posting your answer, you agree to the privacy policy and terms of service.

Not the answer you're looking for? Browse other questions tagged or ask your own question.