Finding range of a function using inequalities

AI Thread Summary
The discussion revolves around determining the range of a function using inequalities, specifically for functions f(x) and g(x) within the interval -1.6 < x < 1.6. The initial attempt concludes that the range for f(g(x)) is the interval [-3, -1.4), but this does not align with the provided solution. Questions arise regarding the breakdown of the f(x) inequality into two parts and the interpretation of results that yield unique integers instead of a continuous interval. Clarification is sought on the reasoning behind these discrepancies and the proper use of notation in mathematical expressions. Understanding these points is crucial for accurately finding the range of the function.
JC2000
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Homework Statement
If ##f : R \Rightarrow R##and ##g:R \Rightarrow R## defined by ##f(x) = |x|## and ##g(x)=(x-3)## then ##{g(f(x)) : -1.6 < x < 1.6}##
Relevant Equations
Given ##f(x)## and ##g(x)## for ## -1.6 < x < 1.6## we get ##0\leq f(x)<1.6##
Now for ##0\leq f(x)< 1## ##\implies## ##g(f(x))=-3## since ## -3\leq f(x)-3<-2##
Again for, ##1\leq f(x)< 1.6## ##\implies## ##g(f(x))=-2## since ## -2 \leq f(x)-3 < -1.4##
Thus the required set is {-3,-2}
My attempt :

Given ##f(x)## and ##g(x)## for ## -1.6 < x < 1.6## we get ##0\leq f(x)<1.6##
Thus, for ##f(g(x))## we get ## -3 \leq g(f(x)) < -1.4##
Thus the required set should be the interval ##[-3, -1.4)##?

My Questions :
1. What have I missed since my answer does not match the given solution.
2. In the given solution why is the ##f(x)## inequality broken into ##0\leq f(x)< 1## and ##1\leq f(x)< 1.6##
3. After splitting the inequality I don't understand how the result is not an interval but two unique integers.
 
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Your answer is correct given the problem stated. The other answer may be the answer to a different question.
 
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JC2000 said:
My attempt :

Given ##f(x)## and ##g(x)## for ## -1.6 < x < 1.6## we get ##0\leq f(x)<1.6##
Thus, for ##f(g(x))## we get ## -3 \leq g(f(x)) < -1.4##
Thus the required set should be the interval ##[-3, -1.4)##?

My Questions :
1. What have I missed since my answer does not match the given solution.
2. In the given solution why is the ##f(x)## inequality broken into ##0\leq f(x)< 1## and ##1\leq f(x)< 1.6##
3. After splitting the inequality I don't understand how the result is not an interval but two unique integers.
You may want to use \mathbb r wrapped around in Latex for the Real numbers, instead of just R. It comes out like this ##\mathbb R##. In some cases you may eliminate ambiguity.
 
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