find the points on the ellipsoid x^2 + (y^2)/4 + (z^2)/9 =1

that are closest to the origin

i'm not sure how to go about solving this problem. it has to do with maxes or mins i'm guessing since that's what we just learned. anyone know what i should do?

i tried taking the derivative and setting it equal to zero and solving for x, y, and z but that gives me (0,0,0) and the answer in the back is (+ or - 1, 0,0)