Describe the following sets in set-builder form:

Question:

Describe the following sets in set-builder form:

(i) A = {1, 2, 3, 4, 5, 6};

(ii) $B=\{1,1 / 2,1 / 3,1 / 4,1 / 5, \ldots\}$;

(iii) C = {0, 3, 6, 9, 12, ...};

(iv) D = {10, 11, 12, 13, 14, 15};

(v) E = {0};

(vi) {1, 4, 9, 16, ..., 100}

(vii) {2, 4, 6, 8 .....}

(viii) {5, 25, 125 625}

Solution:

Set-builder form:

To describe a set, a variable x (each element of the set) is written inside braces. Then, after putting a colon, the common property P(x) possessed by each element of the set is written within braces.

(i) $\{x: x \in N, x<7\}$

(ii) $\left\{x: x=\frac{1}{n}, x \in N\right\}$

(iii) $\left\{x: x=3 n, n \in Z^{+}\right\}$

(iv) $\{x: x \in N, 9

(v) $\{x: x=0\}$

(vi) $\left\{x^{2}: x \in N, 1 \leq n \leq 10\right\}$

(vii) $\{x: x=2 n, n \in N\}$

(viii) $\left\{5^{n}: n \in N, 1 \leq n \leq 4\right\}$

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