state the domain and range of y=-e^(-x), then find the inverse equation of the function.

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embizze | High School Teacher | (Level 1) Educator Emeritus

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State the domain and range of `y=-e^(-x)` and then find its inverse function:

The parent function is `y=e^x` which has a domain of all real numbers and a range y>0. The transformed function has been reflected across the x-axis (`y=-e^x` ) and reflected across the y-axis (`y=e^(-x)` ).

The domain remains the same -- all real numbers. The range becomes y<0 since the graph has been reflected across the x-axis.

To find the inverse function:

`y=-e^(-x)`   We exchange x and y and then solve for y:

`x=-e^(-y)`

`e^(-y)=-x`

`ln(e^(-y))=ln(-x)`

`-y=ln(-x)`

`y=-ln(-x)` which is the inverse function.

Note that for `y=-ln(-x)` the parent function is y=ln(x) which has a domain of x>0 and a range of all real numbers. This function has a domain of x<0 (from the reflection across the y-axis) and a range of all real numbers. (The graph of this function is a reflection of the parent function across the x-axis, but does not affect the range.)

As expected, given the domain of `f(x)=-e^(-x)` as all real numbers and the range f(x)<0, the domain of the inverse function is x<0 and the range is all real numbers.

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The domain is all real numbers and the range is y<0.

The inverse function is `y=-ln(-x)`

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The graphs of the two functions will be reflections across the line y=x:

`y=-e^(-x)` in black, y=-ln(-x) in red, and y=x in green.

 

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