Hello, I'm using maxima as a help to study and got what I believe is a wrong result.
limit( (sin(x)-x)/x³, x, 0);
AFAIU, it should return -1/6:
lim x-> 0 (sinx - x)/x³
= lim x->0 (cosx - 1)/3x² (L'Hopital)
= lim x->0 (-sinx)/6x (L'Hopital)
= -1/6 (as lim x->0 sinx/x = 1)
I've checked it on WolframAlpha and it returns -1/6.