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The following defines a relation on N: x y is square of an integer x, y ∈ N Determine which of the above relations are reflexive, symmetric and transitive.

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प्रश्न

The following defines a relation on N:

x y is square of an integer x, y ∈ N

Determine which of the above relations are reflexive, symmetric and transitive.

योग
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उत्तर

Given, xy is square of an integer x, y ∈ N

R = {(x, y): xy is a square of an integer x, y ∈ N}

It’s clearly (x, x) ∈ R, ∀ x ∈ N

As x2 is square of an integer for any x ∈ N

Thus, R is reflexive.

If (x, y) ∈ R ⇒ (y, x) ∈ R

So, R is symmetric.

Now, if xy is square of an integer and yz is square of an integer.

Then, let xy = m2 and yz = n2 for some m, n ∈ Z

x = `"m"^2/y` and z = `x^2/y`

xz = `("m"^2"n"^2)/y^2`, which is square of an integer.

Thus, R is transitive.

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अध्याय 1: Relations And Functions - Exercise [पृष्ठ १२]

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एनसीईआरटी एक्झांप्लर Mathematics Exemplar [English] Class 12
अध्याय 1 Relations And Functions
Exercise | Q 22. (iii) | पृष्ठ १२

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