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Anonymous
Anonymous asked in Science & MathematicsMathematics · 10 years ago

discrete math help please!?

how many 2-element subsets does {a} have?

how many 2-element subsets does {a,b} have?

how many 2-element subsets does {a,b,c} have?

i dont understand how i would answer this question.

Update:

Hey Meng Tian! i thought the ALL sets automatically contains empty set no matter wat, or i could be wrong. but if so, wouldnt it be {empty set, a}?

1 Answer

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  • ?
    Lv 7
    10 years ago

    1) 0 subset. The set does not even contain 2 elements in the first place.

    2) 1 subset. And that will be {a, b} itself. Note that each set is a subset of itself.

    3) 3 subsets. {a, b}, {b, c} as well as {a, c}.

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