Lingyis on 08 November 2008
| tombi123 said: thanks guys for all your help. The computer programme I'm using is saying that all your answers for the derivative are wrong lol. But it accepted npi/8 for where it wasn't defined. Thanks. Sorry I didn't respond, I fell asleep haha. |
clearly you're not inputing functions the right way for your program, lol.
absolute values are tricky for computers, because they don't get the derivative right. you can use Sqrt(f(x)^2) instead.
anyway, so i just went ahead and checked in mathematica.
>> f[x_] = x*Sqrt[Sin[8x]^2]
and the derivative is basically the same thing i had--i expressed my solution in terms of domain, of course.
if you Simplify[...] that, you get:
(1+8x Cot(8x)) * Sqrt(sin(8x)^2)
where Cot is, of course, the cotangent function, i.e. cos(x)/sin(x).
which is exactly the same thing i had.
the Wii is an epidemic.
