If A = {3, 6, 9, 12, 15, 18, 21}, B = { 4, 8, 12, 16, 20 }, C = { 2, 4, 6, 8, 10, 12, 14, 16 }, D = {5, 10, 15, 20 }; find
(i) A – B (ii) A – C (iii) A – D (iv) B – A (v) C – A (vi) D – A (vii) B – C (viii) B – D (ix) C – B (x) D – B (xi) C – D (xii) D – C

Solutions:

The given sets are:

• A = {3, 6, 9, 12, 15, 18, 21}
• B = { 4, 8, 12, 16, 20 }
• C = { 2, 4, 6, 8, 10, 12, 14, 16 }
• D = {5, 10, 15, 20 }

The difference between two sets A and B is a set denoted by A - B and is obtained by writing the elements of A that are NOT in B in a set.

Thus,

(i) A - B = {3, 6, 9, 15, 18, 21}

(ii) A - C = {3, 9, 15, 18, 21}

(iii) A - D = {3, 6, 9, 12, 18, 21}

(iv) B - A = {4, 8, 16, 20}

(v) C - A = {2, 4, 8, 10, 14, 16}

(vi) D - A = {5, 10, 20}

(vii) B - C = {20}

(viii) B - D = {4, 8, 12, 16}

(ix) C - B = {2, 6, 10, 14}

(x) D - B = {5, 10, 15}

(xi) C - D = {2, 4, 6, 8, 12, 14, 16}

(xii) D - C = {5, 15, 20}

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NCERT Solutions Class 11 Maths Chapter 1 Exercise 1.4 Question 9

If A = {3, 6, 9, 12, 15, 18, 21}, B = { 4, 8, 12, 16, 20 }, C = { 2, 4, 6, 8, 10, 12, 14, 16 }, D = {5, 10, 15, 20 }; find (i) A – B (ii) A – C (iii) A – D (iv) B – A (v) C – A (vi) D – A (vii) B – C (viii) B – D (ix) C – B (x) D – B (xi) C – D (xii) D – C

Summary:

It is given that A = {3, 6, 9, 12, 15, 18, 21}, B = {4, 8, 12, 16, 20}, C = {2, 4, 6, 8, 10, 12, 14, 16}, D = {5, 10, 15, 20}. We have found that
(i) A - B = {3, 6, 9, 15, 18, 21}
(ii) A - C = {3, 9, 15, 18, 21}
(iii) A - D = {3, 6, 9, 12, 18, 21}
(iv) B - A = {4, 8, 16, 20}
(v) C - A = {2, 4, 8, 10, 14, 16}
(vi) D - A = {5, 10, 20}
(vii) B - C = {20}
(viii) B - D = {4, 8, 12, 16}
(ix) C - B = {2, 6, 10, 14}
(x) D - B = {5, 10, 15}
(xi) C - D = {2, 4, 6, 8, 12, 14, 16}
(xii) D - C = {5, 15, 20}