How do we evaluate

lim x-->0 [ cos(2x^3)-1]/[(sin2x^6]

I tried the substitution 2@=2x^3 but that leaves a 'x^2' in the denominator

3 answers

You got me. Aside from expanding into Taylor series and dividing, I don't come up with a trick to evaluate it.
Taylor series is not taught in our curriculum :-(
The same here :-(