Question

solve this problem quickly.please quickly​

Answer 1

Answer:

solution no.1

R={(a,b):a is sister b}

it is a boys school so there are no girl student

there cannot be sister of any student of the school.

Hence, R=Ф, i.e. R is empty relation.

solution no.2

a.)

R={(1,2),(2,1)}

check Reflexive

if the relation in reflexive

then (a,a) ∈ R for every a  ∈ {1,2,3}

since (1,1) ∉ R

∴R is not reflexive

R'

R'= {(a,b):the difference between heights of a and b is less than 3 meters}

the difference between heights of any two student of the school has to be less than 3m (9.8 foot).

so,R'is the universal