Question

Assume each variable has a different value. Which relations below are functions? a. {(a, b), (a, c), (a, d), (a, e)} b. {(a, b), (b, b), (c, b), (d, b)} c. {(a, b), (c, d), (e, f), (g, h)} d. {(a, a), (b, c), (c, c), (d, e)}
A. choice a only

B. choices b and c only

C. choice c only

D. choices b, c, d only

Answer 1

I think its D but im not 100% sure let me know if its right

Answer 2

A function is a relation in which every input value x has at most one output value y.

Consider all options:

a. Relation {(a, b), (a, c), (a, d), (a, e)} is not a function, because input value a has four different output values b, c, d and e.

b. Relation {(a, b), (b, b), (c, b), (d, b)} is a function, because every input value a, b, c and d have at most one output value b.

c. Relation {(a, b), (c, d), (e, f), (g, h)} is a function, because every input value a,  c, e and g have at most one output value b, d, f and g, respectively.

d. Relation {(a, a), (b, c), (c, c), (d, e)} is a function, because every input value a,  b, c and d have at most one output value a, c, c and e, respectively.

Answer: correct choice is D