Originally Posted by

**mark** hi, i've got the question:

write down the equation of the circle which is obtained by applying the given translation to the given circle:

$\displaystyle [-4, 1]$, $\displaystyle x^2 + y^2 - 81 = 0$

the answer i came up with was $\displaystyle (x + 4)^2 + (y - 1)^2 = 81$ and the answer the book gives is $\displaystyle (x + 4)^2 + (y - 1)^2 - 81 = 0$

i would presume these were the same, i was just writing to make sure there wasn't some reason you couldn't express it the way i did, could someone tell me if i'm right please, thanks