हिंदी

Let L be the set of all lines in the XY plane and R be the relation in L defined as R = {(L_1, L_2) : L_1 is parallel to L_2}. Show that R is an equivalence relation.

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प्रश्न

Let L be the set of all lines in the XY plane and R be the relation in L defined as R = {(L1, L2) : L1 is parallel to L2}. Show that R is an equivalence relation. Find the set of all lines related to the line y = 2x + 4.

योग
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उत्तर

(i) Reflexive:

R = {(L1, L2) : L1 is parallel to L2}

R is reflexive, as any line L1 is parallel to itself, i.e., (L1, L1) ∈ R.

∴ R is reflexive.

(ii) Symmetric:

Now, let (L1, L2) ∈ R

⇒ L1 is parallel to L2.

⇒ L2 is parallel to L1.

⇒ (L2, L1) ∈ R

∴ R is symmetric.

(iii) Transitive:

Now, let (L1, L2), (L2, L3) ∈ R

⇒ L1 is parallel to L2. Also, L2 is parallel to L3.

⇒ L1 is parallel to L3.

∴ R is transitive.

Hence, R is an equivalence relation.

The set of all lines related to the line y = 2x + 4 is the set of all lines that are parallel to the line y = 2x + 4.

Slope of the line y = 2x + 4 is m = 2.

It is known that parallel lines have the same slopes.

The line parallel to the given line is of the form y = 2x + c, where c ∈ R.

Hence, the set of all lines related to the given line is given by y = 2x + c, where c ∈ R.

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अध्याय 1: Relations and Functions - EXERCISE 1.1 [पृष्ठ ६]

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एनसीईआरटी Mathematics Part 1 and 2 [English] Class 12
अध्याय 1 Relations and Functions
EXERCISE 1.1 | Q 14. | पृष्ठ ६

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