Question

If A= {1,2,3,4,5,6,7,8,9} a) how many subsets does A have b) how many proper subsets does A have?

Answer 1

if a set has n elements, then it will have 2^n subsets

it will have (2^n) - 1 proper subsets because you are excluding the set itself

Answer 2

is this the answer?

Answer 3

no, you need to replace n with the number of elements in set A

Answer 4

then evaluate

Answer 5

so replace it with the number 9?

Answer 6

yes

Answer 7

ok so the answer would be 2^9 - 1 = 511 ?

Answer 8

for part b)

Answer 9

so a is 511 right?

Answer 10

no what you just calculated is for part b

Answer 11

since there are 2^9 - 1 = 511 proper subsets

Answer 12

ooh ok so what about a ... is it just 9?

Answer 13

no it's when you evaluate 2^n

n = 9

Answer 14

ok so how do we get a?

Answer 15

I just told you

Answer 16

evaluate 2^n when n = 9

Answer 17

511?

Answer 18

512?*