Hi,

f(x) = 3x+4

So I found the inverse:

f(x) = 3x+4

x=3y+4

x-4=3y

y=x-4/3

Then it asks to find the domain and range. So...could someone help me? I'm not sure on how to find them.

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- Aug 14th 2008, 04:31 AMlax600Function Question
Hi,

f(x) = 3x+4

So I found the inverse:

f(x) = 3x+4

x=3y+4

x-4=3y

y=x-4/3

Then it asks to find the domain and range. So...could someone help me? I'm not sure on how to find them. - Aug 14th 2008, 04:44 AMmasters
- Aug 14th 2008, 04:44 AMmoolimanj
The inverse is simply:

f(x)^-1=(Y-4)/3

Try drawing a simple graph of the equation to see where the domain lies.

Note that when Y=4, x=0 - Aug 14th 2008, 04:57 AMmr fantastic
- Aug 14th 2008, 05:17 AMmoolimanj
Good observation Mr F

Apologies, I meant to put the equation as a function of x after I rearranged.

Spot on with the point about the graph - Aug 14th 2008, 07:02 AMlax600
- Aug 14th 2008, 07:11 AMmasters
It would appear that you may choose any real number for x which would make the domain all real numbers.

And in doing so, the range (values for y) would also be any real number making the range all real numbers as well.

$\displaystyle D=\{x|x \in \Re \}$

$\displaystyle R=\{y|y \in \Re \}$