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Relations And Functions

Question
CBSEENMA12032412

Construct a 3 X 2 matrix whose elements are given by straight a subscript straight i space straight j end subscript equals 1 half space left square bracket space straight i minus 3 space straight j space straight i.

Solution

Let A = [ai j ) be required 3x2 matrix, where
straight a subscript ii equals 1 half space left square bracket straight i minus 3 space straight j space vertical line
straight a subscript 11 equals 1 half space vertical line 1 space minus 3 vertical line equals 1 half left parenthesis 2 right parenthesis equals 1. space straight a subscript 12 equals 1 half left square bracket 1 minus 5 right square bracket equals 1 half left parenthesis 5 right parenthesis equals 5 over 2
straight a subscript 21 equals 1 half left square bracket 2 minus 3 right square bracket equals 1 half left parenthesis 1 right parenthesis space space space straight a subscript 22 space equals 1 half space left square bracket 2 minus 6 right square bracket equals 1 half left parenthesis 4 right parenthesis equals 2
straight a subscript 31 equals 1 half left square bracket 3 minus 3 right square bracket equals 1 half left parenthesis 0 right parenthesis equals 0. space space space straight a subscript 32 equals 1 half left square bracket 3 minus 6 right square bracket equals 1 half left parenthesis 3 right parenthesis equals 3 over 2

space space space space space space space space straight A equals open vertical bar table row 1 cell 5 over 2 end cell row cell 1 half end cell 2 row 0 cell 3 over 2 end cell end table close vertical bar

Some More Questions From Relations and Functions Chapter

lf a matrix has 18 elements, what are the possible orders it can have ? What, if it has 5 elements?

If a matrix A has 12 elements, what arc the possible orders it can have 7 What if it has 7 elements ?

Let A be the set of all students of a boys school. Show that the relation R in A given by R = {(a, b) : a is sister of b} is the empty relation and R’ = {(a, b) : the difference between heights of a and b is less than 3 meters} is the universal relation.

Show that the relation R in the set {1, 2, 3} given by R = {(1, 1), (2, 2), (3, 3), (1, 2), (2, 3)} is reflexive but neither symmetric nor transitive.

Show that the relation R in the set {1, 2, 3} given by R = {(1, 2), (2, 1)} is symmetric but neither reflexive nor transitive.

Give an example of a relation which is

(i) Symmetric but neither reflexive nor transitive.
(ii) Transitive but neither reflexive nor symmetric.
(iii) Reflexive and symmetric but not transitive.
(iv) Reflexive and transitive but not symmetric.
(v) Symmetric and transitive but not reflexive.

Let L be the set of all lines in a plane and R be the relation in L defined as R = {(L1, L2) : L1 is perpendicular to L2}. Show that R is symmetric but neither reflexive nor transitive.

 Determine whether each of the following relations are reflexive, symmetric and transitive :

(i) Relation R in the set A = {1, 2, 3,....., 13, 14} defined as

R = {(x, y) : 3 x – y = 0}

(ii) Relation R in the set N of natural numbers defined as R = {(x, y) : y = x + 5 and x < 4} (iii) Relation R in the set A = {1, 2, 3, 4, 5, 6} as R = {(x,y) : y is divisible by x} (iv) Relation R in the set Z of all integers defined as R = {(x,y) : x – y is an integer}

(v) Relation R in the set A of human beings in a town at a particular time given by
(a)    R = {(x, y) : x and y work at the same place}
(b)    R = {(x,y) : x and y live in the same locality}
(c)    R = {(x, y) : x is exactly 7 cm taller than y}
(d)    R = {(x, y) : x is wife of y}
(e)    R = {(x,y) : x is father of y}

Check whether the relation R defined in the set {1, 2, 3, 4, 5, 6} as R = {(a, b) : b = a + 1} is reflexive, symmetric or transitive.