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The function f(x)=(x+4)^2 + 3 is not one-to-one. Identify a restricted domain that makes the function one-to-one, ad find the inverse function.

 Sep 30, 2016
 #1
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f(x)=(x+4)^2 + 3

 

The vertex of this function  is (-4, 3).........it will be one-to-one if we resrict the domain to either   (-inf, -4)  or (-4, inf).....x = -4 could belong to either original domain  and to either domain of the inverse

 

To find the inverse    write "y" for f(x)

 

y = (x + 4)^2 + 3      subtract 3 from both sides

 

y - 3   = ( x + 4)^2      take the pos/neg square roots of both sides

 

±√ [y - 3]  = x + 4      subtract 4 from both sides

 

±√ [y - 3] - 4  = x      "swap" x and y

 

±√ [x - 3] - 4  =  y        for y, write f-1(x)

 

±√ [x - 3] - 4   =  f-1 (x)

 

When we restrict the original domain to (-inf, -4),  -√ [x - 3] - 4 is the inverse

 

When we restrict the original domain to (-4, inf ) ,   √ [x - 3] - 4 is the inverse

 

 

 

cool cool cool

 Sep 30, 2016
 #2
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So x= >= -4 for the restricted domain?

 Sep 30, 2016
 #3
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@CPhill

 Sep 30, 2016

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