x=y^4-1 not sure how to approach this problem

Question

"Given that x=y4-1, solve this for y and state whether it is a function or not."

Answer 1

x = y⁴ - 1

x + 1 = y⁴

 

Now you can take the 4th root of both sides to get an expression for y, but remember that since 4 is an even power, you need to include both the positive and negative 4th roots:

 

±(x + 1)^1/4 = y

 

y is NOT a function because there is more than one value of y for each value of x.