Question

cho A= {x∈ N sao cho x\(^2\) - 4x ≤ 0}

       B={x∈ N / x / ≤ 5}

Answer 1

`@` `\text {Ans}`

`\downarrow`

`\text {A = }` `{x \in NN` `|` `x^2 - 4x \le 0}`

`x^2 - 4x \le 0`

`=> x(x - 4) \le 0`

`=> \text {TH1:} x \le 0`

`\text {TH2: }` `x - 4 \le 0`

`=> x \le 4`

Vậy, `x \in {0; 1; 2; 3; 4}`

`=> A = {1; 2; 3; 4}`

`\text {B = } x \in NN` `|` `x \le 5}`

`=> x \in {0; 1; 2; 3; 4; 5}`

`=> B = {0; 1; 2; 3; 4; 5}`

Answer 2

A={0;1;2;3;4}

B={1;2;3;4;5}