noname1 said:
for what values of n & m will be differentiable for all values of x
nx+m, x<=-1
nx^3+x+2m, X>-1
i have as n = to 0 and m = to 1 is this correct?
Your question doesn't make much sense the way it's written, or maybe I don't understand what you're trying to say.
I'm assuming that m and n are real numbers.
nx + m is differentiable for any values of m and n, regardless of the value of x. If the domain is restricted to x <= -1, it's still differentiable.
nx
3 +x + 2m is differentiable for all values of m and n, regardless of the value of x.
It occurs to me that what you have, but didn't explain very well, is a function whose formula is different on the two intervals. If that's the case, you want to find m and n so that
1) \lim_{x \rightarrow -1^-} f(x)~=~\lim_{x \rightarrow -1^+} f(x)
2) \lim_{x \rightarrow -1^+} f'(x)~=~\lim_{x \rightarrow -1^+} f'(x)
If the first condition is satisfied, your function will be continuous for all x. If the second is satisfied, the derivative will be continuous for all x.