How to check if a function is invertible?

[river compass]

Without derivatives please.
Do i need to check if x + y > 0?
Im doing the problem set right now and I have issues

I know f(y) = x but are there any other requirements?

[strong lily]

you should check "one to one" and "onto" if this two conditions okay,we can say func is invertible

[prisma plover]

U mean
f(g(x))=x
g(f(x))=x

[river compass]

WAit but im lost

In the problem a is equal to 1

But no idea how to calculate b..

I did the other problems thanks to the advice but im stuck on this

Whatever i do i get the wrong answer

[acoustic estuary]

onto means that the range is its entire codomain

i dont think that needed for it to be invertible

e^x doesn't map onto R^1

it only maps onto positive reals

stil invertible though