Question

Exponents help

Answer 1

How does 2^19 / 2^20 = 1/2?

Answer 2

2^19 = 2 multiplied by itself 19 times. Do that on your calculator.

Answer 3

This is for the GRE and I won't have enough time to do that. There must be a quick way I can't remember.

Answer 4

subtract exponets 20-19=1

Answer 5

ok...But that does not equal 1/2.

Answer 6

\[\frac{ 2^{19} }{ 2^{20} }\]

The top part goes away because its taken from the bottom to make the bottom 2^1 because 20-19 is 1, BUT you still need a 1 on top because its still a fraction and you cant just not have anything in the top in a fraction.

Answer 7

Thanks

Answer 8

\[\frac{ a^x }{ a^y }=a^x*a ^{-y}=a ^{x-y}\]
\[\frac{ a^x }{ a^y }=\frac{ 1 }{ a^y*a ^{-x} }=\frac{ 1 }{ a ^{y-x} }\]