Algebraically determine whether the equatoin gives y as a function of x.

Question

Ix+yI=7

 

How do I solve this problem?

Answer 1

|x+y|=7.

If x=0, y=+7 or -7 so a single value of x results in two different values for y.

Similarly, if y=0, x=+7 or y=-7 and a single value of y results in two different values for x. Neither x nor y can be the dependent variable, so it’s not a function.

Another way is to write x+y=7, x+y=-7, implying y=7-x and y=-7-x. y is not a function of x.