Inverse Function Question (1 Viewer)

[kaz1]

For part (ii) I got y= 1±√(1-2x). In Terry Lee's solutions it says y= 1-√(1-2x) but I don't understand why it is minus. Can someone please explain it to me?

 

[lolokay]

for it to be a function, there can only be one y value for every x value so you can't have the ±. I'm not too sure why it's - rather than + though

edit: oh right.. didn't notice the x<=1 part

 

[Pwnage101]

since x is less than or equal 1 for f(x), y is less than or equal to 1 for the inverse, and this only occurs when u take the minus root

 

[lyounamu]

as lolokay said, it has to be either - or + to satisfy the function.

since the domain of the funciton was x<= 1, y<= 0.5

then the inverse's domain and range must be y<= 1 or x<=0.5

if you put x = -5 as a sample, you will see that the inverse should be 1-sqrt(1-2x) rather than 1+sqrt(1-2x)

 

[kaz1]

Thanks for your help people, I get it now.