Thread: Function Help

I do not understand how to answer this question:

f(x) = 1
x + 2

a) find the value of x which must be excluded from the domain of f(x)

b) find the inverse function f-1 (x)

Help would be appreciated on either question

Originally Posted by abbie1212

I do not understand how to answer this question:

f(x) = 1
x + 2

a) find the value of x which must be excluded from the domain of f(x)

b) find the inverse function f-1 (x)

Help would be appreciated on either question

a) The term of the function is a fraction. Keep in mind that the division by zero is not allowed.

b) Take the equation y = f(x). That means



Now swap the variables x and y and solve for y again.

Dear abbie1212,

I assume you have written, f(x)=1/(x+2)

Now you could see that this function does not have a value when x=-2.
(f(x)would be infinite.) Therefore x=-2 must be excluded from the domain of f.

Thanks, but still a bit confused, what is the answer and how?

Originally Posted by abbie1212

Thanks, but still a bit confused, what is the answer and how?

what answer? the question about the function's domain or its inverse?