Analyzing the Setup
Welcome, fellow traveler, to the beautiful world of composite functions! Today, we are going to dissect a problem that perfectly illustrates how functions interact.
We are given f(x)=∣x−1∣ and a piecewise function g(x). Our goal is to understand the nature of h(x)=f(g(x)).
Think of h(x) as a two-stage machine: first, the input x passes through the g machine, and then the output of that machine is fed into the f machine.
The Two-Stage Transformation
Our master equation is h(x)=∣g(x)−1∣. Because g(x) is defined differently for positive and negative inputs, our composite function h(x) must also be defined piecewise.
Let us look at the case where x≥0. Here, g(x)=ex. Substituting this into our master equation, we get:
Now, consider the behavior of ex for x≥0. Since ex≥e0=1, the expression ex−1 is always non-negative.
Thus, the modulus simply vanishes, leaving us with h(x)=ex−1. This is the right branch of our function, starting from the origin and climbing rapidly toward infinity.
The Left-Hand Side
Now, let us shift our focus to the region where x<0. In this domain, g(x)=x+1.
Substituting this into h(x)=∣g(x)−1∣, we get:
The +1 and −1 cancel out, leaving us with h(x)=∣x∣. Since we are in the domain x<0, the definition of the modulus tells us that ∣x∣=−x.
So, for the left side, our function is simply the line h(x)=−x. This is a straight line descending from infinity to the origin.
The Final Verdict
We have now constructed our function:
If you visualize this, you see a V-shaped curve that touches the origin.
Now, let us test for injectivity (one-one). If we draw a horizontal line at y=2, it intersects the graph at two points: one on the left branch and one on the right. Because a horizontal line hits the graph twice, the function is not one-one.
Finally, let us test for surjectivity (onto). The graph starts at y=0 and goes up to infinity. It never touches the negative y-axis.
Since the Range is $