Why everything to power of zero is equal to one?
x to the power a divided by x to the power b is x to the power
(a - b)
When a and b are equal then this is x to the power a divided by
x to the power a, ie 1. x to the power (a - a) = x to the power
zero.
Things which are equal to the same thing are equal to each
other, so 1 = x to the power zero.