SOLUTION: Hi there, I've been trying and trying this problem with no luck. Could you help me out with this, please? Given the function y=(x-11)^2, where x is less than or equal to 11, fi

Algebra ->  Functions -> SOLUTION: Hi there, I've been trying and trying this problem with no luck. Could you help me out with this, please? Given the function y=(x-11)^2, where x is less than or equal to 11, fi      Log On


   



Question 921397: Hi there, I've been trying and trying this problem with no luck. Could you help me out with this, please?
Given the function y=(x-11)^2, where x is less than or equal to 11, find the inverse and its domain.
I keep getting y=plus or minus sqrt(x)-1 which is incorrect.

Found 2 solutions by josgarithmetic, jim_thompson5910:
Answer by josgarithmetic(39617) About Me  (Show Source):
You can put this solution on YOUR website!
Domain of given y is x%3C=11 and range is y%3E=0.

The inverse h(x) of this y has domain x%3E=0 and range h%28x%29%3C=11.

FINDING THE INVERSE, h(x):
x=%28h%28x%29-11%29%5E2, vertical and horizontal components change places.
h%28x%29-11=0%2B-+sqrt%28x%29
highlight%28h%28x%29=11%2B-+sqrt%28x%29%29
---And again, be reminded of the domain and the range. You need to use the MINUS square root form and reject the other branch.

Answer by jim_thompson5910(35256) About Me  (Show Source):
You can put this solution on YOUR website!
The domain of the original function is x%3C=11. This is given to you and this restriction is made to force f(x) to be one-to-one.

The range of the original function is y%3E=0. This is found either through the graph or by knowing that (x-11)^2 is either 0 or positive. You can't square a number and get something negative.

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When you solve for the inverse, you swap x and y and solve for y. Doing that also swaps the domain and range. Why? Because the domain is simply the set of allowed x values (inputs) and the range is the set of possible y values (outputs).

Again, the domain and range swap. This is important.

So the inverse will have the domain of x+%3E=+0 and the range of y+%3C=+11

The range for the inverse is what is important here.


When you swap x and y, then solve for y, you should get this: y+=+%22%22%2B-sqrt%28x%29%2B11

But keep in mind that the range of the inverse is y+%3C=+11. This means negative y values such as y+=+-2 are possible in the range of the inverse.

This is only possible if you pick the negative square root. You cannot generate negative y values with y+=+sqrt%28x%29%2B11. It's impossible. The two pieces are always positive.

So the inverse is

You can rewrite that as


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Let me know if that helps or not. Thanks.

If you need more help, feel free to email me at jim_thompson5910@hotmail.com

My Website: http://www.freewebs.com/jimthompson5910/home.html