f(x)=`underset(h→0)lim(f(x+h)-f(x))/h`

If f is derivable function of x, then underset(hto0)("lim")(f(x+h)-f(x-h))/(h)=

Let fRtoR be a function we say that f has property 1 if underset(hto0)(lim)(f(h)-f(0))/(sqrt(|h|)) exist and is finite. Property 2 if underset(h to 0)(lim)(f(h)-f(0))/(h^(2)) exist and is finite. Then which of the following options is/are correct?

If a function f is differentiable at x= a, then underset(hto0)("lim")(f(a-h)-f(a))/(h)=

Instead of the usual definition of derivative Df(x), if we define a new kind of derivative D^*F(x) by the formula D*f(x)=lim_(h->0)(f^2(x+h)-f^2(x))/h ,w h e r ef^2(x) mean [f(x)]^2 and if f(x)=xlogx ,then D^*f(x)|_(x=e) has the value (A)e (B) 2e (c) 4e (d) none of these