Q8 of 68 Page 27

If R2 = {(x, y) | x and y are integers and x2 + y2 = 64} is a relation. Then find R2.

Given: R2 = {(x, y) | x and y are integers and x2 + y2 = 64} is a relation


To find: R2


Explanation: Given R2 = {(x, y) | x and y are integers and x2 + y2 = 64}


This means set R2 contains all whole numbers such that the relation between the elements of the set satisfy the condition x2 + y2 = 64, so


x2 + y2 = 64


y2 = 64- x2



This is possible only when


64-x2≥0


64≥ x2


x2≤64


Taking square root on both sides, we get


x≤±√64


x≤±8


i.e., -8≤x≤8


So, x [-8,8]


Now for corresponding values of x, y becomes


When x = ±8



So, two of the elements of R2 = (-8, 0), (8, 0)


When x = ±7





Now as y is an integer, so x cannot take values, ±7


When x = ±6






Now as y is an integer, so x cannot take values, ±6


When x = ±5






Now as y is an integer, so x cannot take values, ±5


When x = ±4






Now as y is an integer, so x cannot take values, ±4


When x = ±3






Now as y is an integer, so x cannot take values, ±3


When x = ±2






Now as y is an integer, so x cannot take values, ±2


When x = ±1






Now as y is an integer, so x cannot take values, ±5


When x = 0







So, two of the element of R2 = (0, 8), (0, -8)


Hence complete set is


R2 = {(0, 8), (0, -8), (-8,0), (8, 0)}


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