CBSE Class 11 Maths Chapter Sets - NCERT Exercise 1.4 (Q 9 - Q 12) (#eduvictors)(#class11Maths)

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

NCERT Solutions

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


Answer: 
(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

Answer: 
(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?

Answer:  
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.

Answer: 
(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


☞See also:
Special Mathematical Constants

 SETS (NCERT Ex 1.1)
 SETS (NCERT Ex 1.2)
 Different Types of Sets
 SETS (NCERT Ex 1.3)

 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)