Q3 of 50 Page 11

Let P = {a, b, c}, Q = {g, h, x, y} and R = {a, e, f, s}. Find the following:

(i) P R


(ii) Q + R


(iii) R (P + Q)

(i) The set which will be obtained from P R is called as a complement set. It indicates the elements which are only a part of the set P and doesn’t belong to R.


Mathematically,


P R = {x|x p but x R}


We are given


P = {a, b, c},


R = {a, e, f, s}


So using the given values


P R = {a, b, c} {a, e, f, s}


= {b, c}


(ii) The above statement can also be written as (Q Ո R). An intersection operation between two sets gives a set which contain the elements which are common to both the sets.


We are given


Q = {g, h, x, y}


R = {a, e, f, s}


So using the value given


(Q Ո R) = {g, h, x, y} Ո {a, e, f, s}


= Ø


It’s called as a disjoint set as both the sets Q and R doesn’t have any elements in common.


(iii) Before proceeding we will split the entire operation into two halves. We know that the statement (P + Q) can be written as (P Ո Q) and it will give a set of all common elements


We are given that


P = {a, b, c},


Q = {g, h, x, y}


R = {a, e, f, s}


So using the values given


(P Ո Q) = {a, b, c} Ո {g, h, x, y}


= Ø [disjoint sets as there are no common elements]


Now the statement R (P + Q) shows a difference operation of two sets. The difference operation will give elements which are a part of set R only and doesn’t exist in (P Q).


So using the values given


R (P + Q) = R (P Q)


= {a, e, f, s} Ø


= {a, e, f, s} (.ans)


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