Question

(BEST ANSWER GETS MEDAL!) Is {(8,9),(9,2),(-3,2),2,2)} a function?

Answer 1

Also is x = 5 a fuction?

Answer 2

{(8,9),(9,2),(-3,2),2,2)} <---- notice the (x,y) pair

does it have repeat x-values? if it does, then is NOT function, if it doesn't, then it is

Answer 3

@jdoe0001 so is is a function?

Answer 4

well, does it have repeat x-values?

Answer 5

{(8,9),(9,2),(-3,2),(2,2)}
x,y x,y x,y x,y

see any x-values repeated?

Answer 6

Nope

Answer 7

you're correct.... x-values are 8,9,-3 and 2
no repeats, thus it IS a function :)

Answer 8

Thank you so much!

Answer 9

yw

btw x = 5 is a function as well
a vertical line with an undefined slope

Answer 10

hmm actually a vertical line with a slope of 0 rather

Answer 11

Oooh ok! So if we have x = 5, how would we evaluate it for f(2)?

Answer 12

\(\large {
\begin{array}{llll}
x&y
\\\hline\\
5&1\\
5&2\\
5&2,000\\
5&2,000,000\\
5&\pm \infty
\end{array}\implies f(2)=5
}\)

Answer 13

Thank you so much!

Answer 14

yw

Answer 15

hmmm

Answer 16

actaully f(2) = 5 is a bit misleading

f(2) implies x = 2 BUT, x is never anything other than 5

Answer 17

x=5 is NOT a function because its graph is a vertical line, which fails the vertical line test. If x = 5, then ALL of the points would have repeating x-values: (5, 1), (5, 2), (5, 3) -- which is NOT allowed in functions.
y=5 would be a function, because it's horizontal. But x=5 is NOT a function.

Also, vertical lines do have undefined slope; horizontal lines have zero slope.