Question

fie multimile A={ n € N | 1/7 < 1/n < 1/2} si B={n € N | 3/2 > 5/n > 2/3}
a) dererminati elementele multimilor A si B
b) determinati A reunit cu B, A intersectat cu B , A\B si B\A

Answer 1

Răspuns:

Explicație pas cu pas:

A={ n € N | 1/7 < 1/n < 1/2}

1/7 < 1/n

n < 7

1/n < 1/2

n > 2

2 < n < 7

A = {3; 4; 5; 6}

____________

B={n € N | 3/2 > 5/n > 2/3}

3/2 > 5/n

3n > 15

n > 5

5/n > 2/3

2n < 15

n < 15/2

5 < n < 15/2

B = {6; 7}

______________

A U B = {3; 4; 5; 6; 7}

A ∩ B = {6}

A \ B = {3; 4; 5}

B \ A = {7}