Newtons law of cooling

[soccerboi]

What's the eqn for it?
From my class notes i have : dT/dt = k(T-T_s)
From another book, they have it as: dT/dt = -k(T-T_s)

But i just did a question with both and they both get the same answer, unless i made an error somewhere...

So, im confused about which one to use? Or is either perfectly fine as they yield the same answer? If so, why do they get the same answer?Doesn't they negative change the sign o the final answer???

Thanks in advance

[max payne]

Either one. The only thing that is different is that the sign (+/-) of 'k' will be different when solving however when you chuck it back in the equation, they will be the same. The initial conditions will always give you the correct sign.

[Biceps]

Both work

[sandaygirl]

yeah both are the same ! It confused me to !