Explain when a relation is not a function?

Solution:

A function is always a relation but a relation is not always a fucntion.

For example

we can make a realtion of student roll number and their marks obtained in mathematics.

So we can have pairs like (a,b), (c,d)..etc.

Its a realtion but it may not be function. Because function follows that for same input there should not be diffrent output. But this doesn't holds a necessary condition in case of relation.

Because two diffrent students with two diffrent Roll number may have same marks.

Every domain element is paired with only one range element. No two pairs share the same domain element.

Step-by-step explanation:

in simplified version   it would be x ≤-4

step-by-step explanation:

multiply each term in x ≤-4 by -1