Posted by **Anonymous** on Saturday, August 17, 2013 at 3:17pm.

Select the relation that is a function.

a.

{(21, 11), (21, 10), (21, 9), (21, 8)}

c.

{(-6, -5), (3, 2), (10, 8), (3, 3)}

b.

{(-2, -1),(5, -1), (16, 3), (-3, -9)}

d.

{(5, 10), (-3, 10), (-3, -10), (4, 7)}

- Math -
**Steve**, Saturday, August 17, 2013 at 4:29pm
hint: each element must have a single image.

- Math -
**Anon**, Saturday, August 17, 2013 at 7:07pm
Just tell the answer

- Math -
**Anon**, Saturday, August 17, 2013 at 7:22pm
cause i dont understand what you saying

- Math -
**Steve**, Saturday, August 17, 2013 at 7:52pm
Note that in (a) (21,11) and (21,10) indicate that f(21) = 11 and f(21) = 10.

That can't be so, for a function.

In (c), we have f(3) = 2 and f(3) = 3

In (b) there is only one mapping for each element.

In (d) we have f(-3)=10 and f(-3)=-10.

each element can have only one image under the mapping. That is, the relation maps the first value to the second value in each pair.

A value can only be mapped to a single image. Better study the chapter on relations, mapping, images, etc. and what makes a function more restrictive than just a general relation.

- Math -
**Anon**, Saturday, August 17, 2013 at 8:05pm
so b?

- Math -
**Steve**, Saturday, August 17, 2013 at 8:12pm
That'd be my guess, unless you have b and c switched. They are listed out of order.

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