# Homework Help: Dx/dt = 3 m/s solve for x(t)

1. Feb 17, 2010

### ct fisher

Hello out there,and pardon my dementia but:

I am a middle aged guy, bordering well on old now, who graduated from professional school in 1986 and I was already an older than most student at that time. I had one semester of calculus in 1973 and slipped through with a C major.
My calculus is limited to very basic diff and integ and a young upstart resident handed me this today:

dx/dt = 3 m/s solve for x(t)

I am lost. The answer is not zero or some constant I am sure. The two variable business changes everything, right?

If this is a differential equation, nothing in my old notes is helping to enlighten me. Any help would be appreciated.
If this upstart resident has made a fool of me and the problem is bogus, he will regret it. He says he could not answer it so I don't know what is up his sleeve. I'm thinking that the problem may be just a lot of bull.Thank you. CTF

2. Feb 17, 2010

### Coto

I will bite.

Integrate both sides to obtain:

$$\int_{x'=0}^{x} dx' = \int_{t'=0}^{t} 3 dt'$$

That is, $$x' |_{0}^{x} = 3 t' |_{0}^{t} \implies x(t) = 3t$$.

Edit: I post this full solution because I believe the question is simple enough that there's no point beating around the bush.