Let a = r−{0}, the set of all nonzero real numbers, and consider the following relations on a × a. decide in each case whether r is an equivalence relation, justifying your answers. in the case that r is an equivalence relation, find the equivalence classes. (a) (a, b)r(c, d) if and only if ad = bc

Step-by-step explanation:

Let A = R−{0}, the set of all nonzero real numbers, and consider the following relations on A × A.

Given that (a,b) R (c,d) if

Or (a,b) R (c,d) if determinant

a) Reflexive:

We have (a,b) R (a,b) because ab-ab =0 Hence reflexive

b) Symmetric

(a,b) R (c,d) gives ad-bc =0

Or da-cb =0 or cb-da =0 Hence (c,d) R(a,b). Hence symmetric

-18 degrees is the answer : )

i'm not sure i quite understand, could you provide more information?