As shown in the title, how do I find the sum of:
∞∑k=1k2k+1=1
Answer
HINT:
Note that for |x|<1, f(x)=∑∞k=1xk=x1−x implies that
x2f′(x)=∞∑k=1kxk+1
Then, let x=1/2
I have injection f:A→B and I want to get bijection. Can I just resting codomain to f(A)? I know that every function i...
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