A theorem is defined as an existing fact that was proved to be correct through experimentation or mathematical reasoning. In this case, we can say that a theorem can be proven by geometric proof as it is required for people to consider it as a fact. Answer is true.
Yes, is subtraction, to get their "difference".
first off, let's convert the mixed fractions, to "improper", and then subtract.

Step-by-step explanation:
if b+c=0
b=-c
x^b=x^-c
so
1/[2(x^b)+1]