Subsets Math Question?

Question

Suppose A- {2,5,7,9,13,25,26}

a.Find n(A)

b. true or false : 9 is subset of A

c. true or false : 20 is subset of A

d. true or false : 26 is subset of A

I would like how you did it. Especially a.

Answer 1

a. I am guessing you are using n to count A (this is not standard notation), so n(A)=7 (we are just counting the number of unique elements in A)

b,c,d all false: 9, 20, and 26 are numbers, not sets.  A subset, is, as the name implies, itself a set.

Incidentally (and this may have been what you meant) {9} and {26} are subsets of A, and {20} is not.

Answer 2

n(A)=7 because there are seven elements in A

TRUE ( 9 is part of A)

FALSE

TRUE

ANSWER