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Sets Miscellaneous Exercise Class 11

1.Sets Miscellaneous Exercise Class 11

Learn,”Sets Miscellaneous Exercise Class 11″ Understand subset,Difference set,union and intersection set illustrations easily.

Also Read This Article:-  Set

2.Sets Miscellaneous Exercise Class 11 Illustrations

Illustration: 1. Decide, among the following sets, which sets are subsets of one another:
A = \{x : x \in \text{ R } \text{ and } x \text{ satisfy } x^2 - 8x + 12 = 0\}
B = \{2, 4, 6\}, \quad C = \{2, 4, 6, 8, \dots\}, \quad D = \{6\}
Solution: x^2 - 8x + 12 = 0
\implies x^2 - 6x - 2x + 12 = 0
\implies x(x - 6) - 2(x - 6) = 0
\implies (x - 2)(x - 6) = 0
\implies x = 2, 6
A = \{2, 6\}, \quad B = \{2, 4, 6\}, \quad C = \{2, 4, 6, 8, \dots\}, \quad D = \{6\}
अतः A \subset B, \quad A \subset C, \quad B \subset C, \quad D \subset A, \quad D \subset B, \quad D \subset C
Illustration: 2. In each of the following, determine whether the statement is true or false. If it is true, prove it, if it is false, give an example.
Illustration: 2 (i) If x \in A and A \in B, then x \in B
Solution: False
Because a set cannot be a member of another set in this manner; a set can be a subset, superset, or equivalent set. For example:
C = \{1, 2, 3\} and D = \{1, 2, 3, 4\}, then C \subset D.
Illustration: 2 (ii) If A \subset B and B \in C, then A \subset C.
Solution: False
B cannot be an element of another set, i.e., B \notin C.
Illustration: 2 (iii) If A \subset B and B \subset C, then A \subset C.
Solution: True
x \in A \implies x \in B \quad [\because A \subset B]
and x \in B \implies x \in C \quad [\because B \subset C]
\therefore A \subset C
Illustration: 2 (iv). If A \not\subset B and B \not\subset C, then A \not\subset C.
Solution: False
Example: A = \{2, 4, 6\}, \quad B = \{a, b, c\}, \quad C = \{4, 6\}
\therefore A \not\subset B and B \not\subset C, but A \not\subset C (A can be or not subset of C).
Illustration: 2 (v). If x \in A and A \not\subset B, then x \in B.
Solution: False
For example: A = \{8, 9, 10\}, \quad B = \{x, y, z\}
A \not\subset B. \therefore Any element of A cannot be an element of B.
Illustration: 2 (vi) If A \subset B and x \notin B, then x \notin A.
Solution: True
x \notin B \implies x \notin A \quad [\because A \subset B]
Illustration: 3. Let A, B and C be the sets such that A \cup B = A \cup C and A \cap B = A \cap C. Show that B = C.
Solution: A \cup B = A \cup C
\implies (A \cup B) \cap C = (A \cup C) \cap C
\implies (A \cap C) \cup (B \cap C) = C \quad [\because (A \cup C) \cap C = C]
\implies (A \cap B) \cup (B \cap C) = C \quad \dots \text{(1)}
[\because A \cap C = A \cap B]
Again A \cup B = A \cup C
(A \cup B) \cap B = (A \cup C) \cap B
\implies B = (A \cap B) \cup (C \cap B)
[\because (A \cup B) \cap B = B]
\implies B = (A \cap B) \cup (B \cap C) \quad \dots \text{(2)}
From (1) and (2), we get
B = C
Illustration: 4. Show that the following four conditions are equivalent:
(i) A \subset B
(ii) A - B = \phi
(iii) A \cup B = B
(iv) A \cap B = A
Solution: Let A \subset B and x \in A \implies x \in B
\implies x \in A \land x \in B \quad [\because A \subset B]
\implies x \in A \cap B
\therefore A \subset A \cap B \quad \dots \text{(1)}
Let x \in A \cap B
Then x \in A \cap B \implies x \in A \land x \in B
\implies x \in A
\therefore A \cap B \subset A \quad \dots \text{(2)}
From (1) and (2), we get:
A \cap B = A
(ii) Let A \cap B = A
x \in A \implies x \in A \cap B \quad [\because A = A \cap B]
\implies x \in A \land x \in B
\implies x \in B
A \subset B
A \subset B \implies A \cap B = A
Again x \in A - B \implies x \in A \land x \notin B
\implies x \in B \land x \notin B \quad [\because x \in A \implies x \in B \text{ because } A \subset B]
\implies x \in \phi
\therefore A - B = \phi \quad \dots \text{(3)}
\phi \subset A - B \quad [\because \phi \text{ is subset of every set}] \quad \dots \text{(4)}
From (3) and (4), we get:
A - B = \phi
Similarly A \subset B \implies A - B = \phi \quad \dots \text{(5)}
A - B = \phi \implies A - B \text{ has not any element}
\therefore A has not any element which is not in B
\implies A \text{ has each element which is in } B
\implies A \subset B
\therefore A - B = \phi \implies A - B \dots \text{(6)}
From (5) and (6), we get:
A \subset B \iff A - B = \phi
(iii) Let A \subset B then
x \in A \cup B \implies x \in A \lor x \in B
\implies x \in B \quad [\because A \subset B]
\therefore A \cup B \subset B \quad \dots \text{(1)}
Let x \in B then
x \in B \implies x \in A \cup B \quad [\text{By def.}]
\therefore B \subset A \cup B \quad \dots \text{(2)}
From (1) and (2), we get:
A \cup B = B
Again A \cup B = B then
x \in A \implies x \in A \cup B \quad [\because A \subset A \cup B]
\implies x \in B \quad [\because A \cup B = B]
\therefore A \subset B
Similarly
A \subset B \iff A \cup B = B
Illustration: 5. Show that for any sets A and B, if A \subset B, then C - B \subset C - A.
Solution: If A \subset B
C - B = \{x : x \in C \land x \notin B\}
= \{x : x \in C \land x \notin A\} \quad [\because A \subset B]
= \{x : x \in C - A\}
\implies C - B \subset C - A
\implies A \subset B \implies C - B \subset C - A

Illustration: 6. Show that for any sets A and B:
A = (A \cap B) \cup (A - B) and A \cup (B - A) = A \cup B
Solution: Let x \in (A \cap B) \cup (A - B)
\implies x \in (A \cap B) \lor x \in (A - B)
\implies (x \in A \land x \in B) \lor (x \in A \land x \notin B)
\implies x \in A
\implies (A \cap B) \cup (A - B) \subset A \quad \dots \text{(1)}
Again let x \in A
x \in (x \in A \land x \in B) \lor (x \in A \land x \notin B)
\implies x \in (A \cap B) \lor x \in (A - B)
\implies x \in (A \cap B) \cup (A - B)
\therefore A \subset (A \cap B) \cup (A - B) \quad \dots \text{(2)}
From (1) and (2), we get:
A = (A \cap B) \cup (A - B)
Let x \in A \cup (B - A)
\implies x \in A \lor x \in (B - A)
\implies x \in A \lor (x \in B \land x \notin A)
\implies x \in A \cup B \quad [\text{ By def. }]
A \cup (B - A) \subset A \cup B \quad \dots \text{(3)}
x \in A \cup B \implies x \in A \lor x \in B
\implies x \in A \lor (x \in B \land x \notin A)
\implies x \in A \lor (x \in B - A)
\implies x \in A \cup (B - A)
\therefore A \cup B \subset A \cup (B - A) \quad \dots \text{(4)}
From (3) and (4), we get:
A \cup (B - A) = (A \cup B)
Illustration: 7. Using properties of sets, show that:
Illustration: 7 (i). A \cup (A \cap B) = A
Solution: A \cup (A \cap B) = A
= (A \cup A) \cap (A \cup B) \quad [\text{By distributive law }]
\implies A \cap (A \cup B)
\implies A
\therefore A \cup (A \cap B) \subset A \quad \dots \text{(1)}
A \implies A \cap (A \cup B)
\implies (A \cup A) \cap (A \cup B)
\implies A \cup (A \cap B) \quad [\text{By distributive law}]
\implies A \cup (A \cap B)
\therefore A \subset A \cup (A \cap B) \quad \dots \text{(2)}
From (1) and (2), we get:
A = A \cup (A \cap B)
Illustration: 7 (ii). A \cap (A \cup B) = A
Solution: A \cap (A \cup B) = A
A \cap (A \cup B)
= (A \cap A) \cup (A \cap B)
\implies A \cup (A \cap B)
\implies A
\therefore A \cap (A \cup B) \subset A \quad \dots \text{(3)}
Let A
\implies A \cup (A \cap B)
\implies (A \cap A) \cup (A \cap B)
\implies A \cap (A \cup B)
A \subset A \cap (A \cup B) \quad \dots \text\{(4)\}
From (3) and (4), we get:
A \cap (A \cup B) = A
Illustration: 8. Show that A \cap B = A \cap C need not imply B = C.
Solution: Let A = \{x, y\}, B = \{x, z\}, C = \{x, a\}
A \cap B = \{x, y\} \cap \{x, z\}
= \{x\}
and A \cap C = \{x, y\} \cap \{x, a\}
= \{x\}
\implies A \cap B = A \cap C, but B \neq C
Illustration: 9. Let A and B be sets. If A \cap X = B \cap X = \phi and A \cup X = B \cup X for some set X, show that A = B.
Solution: A \cup X = B \cup X
(A \cup X) \cap A = (B \cup X) \cap A
\implies A = (B \cup X) \cap A \quad [\because (A \cup X) \cap A = A]
A = (B \cap A) \cup (A \cap X) \quad [\text{By distributive law}]
= (A \cap B) \cup \phi \quad [\because A \cap X = \phi]
A = A \cap B \quad \dots \text\{(1)\}
A \cup X = B \cup X
(A \cup X) \cap B = (B \cup X) \cap B
\implies (A \cup X) \cap B = B \quad [\because (B \cup X) \cap B = B]
(A \cap B) \cup (B \cap X) = B \quad [\text{By distributive law }]
\implies (A \cap B) \cup \phi = B \quad [\because B \cap X = \phi]
\implies A \cap B = B \quad \dots \text\{(2)\}
From (1) and (2), we get:
A = B
Illustration: 10. Find sets A, B and C such that A \cap B, B \cap C and A \cap C are non-empty sets and A \cap B \cap C = \phi.
Solution: A = \{1, 2\}, \quad B = \{1, 3\}, \quad C = \{2, 3\}
A \cap B = \{1, 2\} \cap \{1, 3\} = \{1\}
B \cap C = \{1, 3\} \cap \{2, 3\} = \{3\}
A \cap C = \{1, 2\} \cap \{2, 3\} = \{2\}
And A \cap B \cap C = \{1, 2\} \cap \{1, 3\} \cap \{2, 3\} = \phi
 \implies B \cap C = \{3\}
A \cap C = \{1, 2\} \cap \{2, 3\}
\implies A \cap C = \{2\}
\implies \text{But } A \cap B \cap C = \phi
By solving the above illustrations, one can understand Sets Miscellaneous Exercise Class 11.

Also Read This Article:-  Properties of Sets Class 11 with Proof

3.Practice Questions of Sets Miscellaneous Exercise Class 11 for Students:

(1.)Let P(A)=P(B),Prove that A=B
(2.)For any set A and B is it true P(A) \cup P(B) = P(A \cup B) ? Clarify your answer.
By solving the above questions,you can understand the Sets Miscellaneous Exercise Class 11 well because the concept is well understood when you solve it practically.
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Also Read This Article:-  Basic Operation On Sets: Examples and History of Sets

4.Frequently Asked Questions Related to Sets Miscellaneous Exercise Class 11:

Q:1.What is a power set?

Ans:The collection of all subsets of any set A is called the power set of A.The power set of A is denoted by P(A).

Q:2.Define the union of sets

Ans:The union of two sets A and B is the set which consists of all these elements which are either in A or in B (including those which are in both).

Q:3.Define the intersection of sets.

Ans:The intersection of two sets A and B is the set of all those elements which belong to both A and B.
By answering the above questions,you can know about the primary terms of Sets Miscellaneous Exercise Class 11.

5.छात्र-छात्राओं से आज का प्रश्न (Today’s Question to Students):

🎯 विनर्स कॉर्नर:क्या आप इस सवाल का सही जवाब दे सकते हैं?अपने नाम के साथ नीचे कमेंट करें!सही जवाब देने वाले Top Students के नाम हमारी आगे post/is article ke update में Photo ya Special Mention के साथ publish की जाएगी।अपना जवाब अभी दर्ज करें!👇
यदि x * y = \sqrt{\frac{(x + y)(y^2 - 12x)}{(x - 2)(y - 2)}}
तो 5 * 9 का मान होगा:
(If x * y = \sqrt{\frac{(x + y)(y^2 - 12x)}{(x - 2)(y - 2)}}, so the value of 5 * 9 would be)
*पिछली प्रश्नोत्तरी का हल*
\frac{?}{32} = \frac{72}{?}
\therefore (?)^2 = 32 \times 72
\therefore ? = \sqrt{32 \times 72}
= \sqrt{2 \times 2 \times 2 \times 2 \times 2 \times 2 \times 2 \times 2 \times 3 \times 3}
= 48
*Previous Quiz Solution*
\frac{?}{32} = \frac{72}{?}
\therefore (?)^2 = 32 \times 72
\therefore ? = \sqrt{32 \times 72}
= \sqrt{2 \times 2 \times 2 \times 2 \times 2 \times 2 \times 2 \times 2 \times 3 \times 3}
? = 48
*”This article has been prepared by **Satyam Coaching Centre** on the **Satyam Mathematics** blog.”*

 

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