Question

I can't solve no.7
pls help me

Answer 1

belongs to symbol be -  #

 let a function be  f(x,y) , x#R,y#R 
Then f is binary on R if f(x,y) # R

Here , a # R , b # R

f(a,b)=a0b = min (a,b)

so it is either a or b depending on which is minimum

As , a , b # R

aob # R

So , o is a binary operation on R as A # R , b # R , aob also belongs to R