Class 11  Maths Chapter Sets - NCERT Exercise 1.4 (Q 9 - Q 12)

Q9: 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

(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}

Q10: If X= { a, b, c, d } and Y = { f, b, d, g}, find
(i) X – Y
(ii) Y – X
(iii) X ∩ Y

(i) X – Y = {a,c}

(ii) Y – X = {f , g}

(iii) X ∩ Y = {b,d}

Q11: If R is the set of real numbers and Q is the set of rational numbers, then what is R – Q?

R: Set of real numbers
Q: Set of rational numbers
Therefore, R – Q is a set of irrational number.

Q12: State whether each of the following statement is true or false. Justify your answer.
(i) { 2, 3, 4, 5 } and { 3, 6} are disjoint sets.
(ii) { a, e, i, o, u } and { a, b, c, d }are disjoint sets.
(iii) { 2, 6, 10, 14 } and { 3, 7, 11, 15} are disjoint sets.
(iv) { 2, 6, 10 } and { 3, 7, 11} are disjoint sets.

(i) False
As 3 ∈ {2,3,4,5} and 3∈ {3,6}
⇒ {2,3,4,5}  ∩ {3,6} = {3}

(ii) False
As a ∈ {a,e,i,o,u} and a ∈ {a,b,c,d}
⇒{a,e,i,o,u} ∩ {a,b,c,d} = {a}

(iii) True
As {2,6,10,14} ∩  {3,7,11,15} = φ.

(iv) True
As {2,6,10} ∩ {3,7,11} = φ

Special Mathematical Constants
SETS (Unit Test Paper)
SETS (VENN DIAGRAMS)
SETS (Operations of Sets)
SETS (NCERT Ex 1.4 Q1-Q5)
SETS (NCERT Ex 1.4 Q6-Q8)  