Hi, everyone-
I have a quick question. When you solve for the derivative (as a linear transformation) using the limit definition of derivative, how does it go?
For example, let p_k be defined as the projection function from Rn to R, projecting onto kth coordinate of the input value...
How do I prove every isometry from R->R is of the form f(x)=a+-x , regardless of the metric?
I know it has to do with considering d_1(0,x_1)=d_2(0, f(x_1)), but beyond that I am lost.
So, I know that R and null are clopen, but now to prove they are the only clopen subsets of R... without the idea of boundary points? I know how to do it with boundary points, but can it be done without?