Wrong answer?

[sajib_mostofa]

I just did the 2010 NEAP exam 1 and for Q3c, the graph has a closed circle at (2,2) according to the solutions. But shouldnt it be at (2,4)?

[Elnino_Gerrard]

I dont  even    get how they got the rule?

how do u know u have to take the negative root of (x-2)²

[Linkage1992]

The equation of the graph will simply be y = x. The point (2,4) doesn't lie on this line.
You have to sub in the value for which the domain of f(x) ends, and this is at x = 2, so you get the endpoint as (2,2)

[sajib_mostofa]

@Elnino_gerrard, The domain of the origin is from , which becomes the range of the inverse. Hence you take the negative square root.

[sajib_mostofa]

The equation of the graph will simply be y = x. The point (2,4) doesn't lie on this line.
You have to sub in the value for which the domain of f(x) ends, and this is at x = 2, so you get the endpoint as (2,2)

How do you know that (2,4) doesn't lie on the line?

[Linkage1992]

I dont  even    get how they got the rule?

how do u know u have to take the negative root of (x-2)²

The domain of the graph is (-infinity, 2) as you found from the previous question. This means the range of the inverse function will have to be (-infinity, 2). Thus, you have to choose the option which gives this range, and so you take the negative root, as the other option doesn't give you the required range.

[Linkage1992]

The equation of the graph will simply be y = x. The point (2,4) doesn't lie on this line.
You have to sub in the value for which the domain of f(x) ends, and this is at x = 2, so you get the endpoint as (2,2)

How do you know that (2,4) doesn't lie on the line?

The equation is y = x.  4 does not equal 2 and so that point cannot lie on the line.

[Elnino_Gerrard]

I dont  even    get how they got the rule?

how do u know u have to take the negative root of (x-2)²

The domain of the graph is (-infinity, 2) as you found from the previous question. This means the range of the inverse function will have to be (-infinity, 2). Thus, you have to choose the option which gives this range, and so you take the negative root, as the other option doesn't give you the required range.

Isnt it just like f(g(x))
How do we know that its the domain of the inside function that becomes the domain of the the whole function? :|:(
Im so lost

[Elnino_Gerrard]

I mean we aint finding an inverse here so how does the whole domain range swapping thing come into play?

[Souljette_93]

I dont  even    get how they got the rule?

how do u know u have to take the negative root of (x-2)²

The domain of the graph is (-infinity, 2) as you found from the previous question. This means the range of the inverse function will have to be (-infinity, 2). Thus, you have to choose the option which gives this range, and so you take the negative root, as the other option doesn't give you the required range.

Isnt it just like f(g(x))
How do we know that its the domain of the inside function that becomes the domain of the the whole function? :|:(
Im so lost

that's the rule.