Question

which of the following represents a function for x,y\(\in \Re\):
a)F={(x,y):x+y<4}
b)F={(x,y): \(\frac{x^2}{4}+\frac{x^2}{4}=1\)}
c)F={(x,y):x+y=2}
d)F={(x,y):\(x^2+y^2=4\)}

Can someone please answer this with appropriate explanation?

Answer 1

Given sets X and Y, a function from X to Y is a set of ordered pairs F of members of these sets such that for every x in X there is a ***unique*** y in Y
for which the pair (x, y) is in F

Answer 2

for example d is not a function
as u can see for x of its domain there is 2 y's

Answer 3

Thanks, @mukushla I get it. for 1 value of x we need to have only one value of y.. So, clearly its c. LOL.. It is too easy. And i had studied these in grade 9.. How could i forget.. I need to revise those lessons..
Anyways thanks!

Answer 4

ur welcome dear