Answer
a) Restrict the domain of \( f(x) = 2x^2 \) to \( x \geq 0 \).
b) The inverse of \( p(x) = \left(\frac{1}{2}\right)^x \) is \( p^{-1}(x) = \log_{\frac{1}{2}}(x) \).
c) If \( g^{-1}(x) = 2x - 4 \), then \( g(x) = \frac{x + 4}{2} \).
Solution
We are given the functions f(x) = 2x² and p(x) = (1/2)ˣ. We wish to:
a) Restrict the domain of f so its inverse is a function.
b) Find the inverse of p in the form p⁻¹(x) = …
c) Given g⁻¹(x) = 2x – 4, find g(x).
Let’s work through each part step by step.
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Part (a)
For a function to have an inverse that is also a function, the function must be one-to-one (injective). The function f(x) = 2x² is not one-to-one over the real numbers because, for example, f(2) = 8 and f(–2) = 8. A common remedy is to restrict the domain so that the function is either only increasing or only decreasing.
A common restriction is to choose x ≥ 0, which gives a monotonically increasing function. Thus, by restricting the domain to [0, ∞), f becomes one-to-one and its inverse is defined.
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Part (b)
We wish to find the inverse of p(x) = (1/2)ˣ. The steps are:
1. Begin with y = (1/2)ˣ.
2. In order to solve for x, take the logarithm base (1/2) on both sides:
x = log₍₁/₂₎(y).
Since we want the inverse function written as p⁻¹(x), we interchange x and y:
p⁻¹(x) = log₍₁/₂₎(x).
Thus, the inverse is:
p⁻¹(x) = log₍₁/₂₎(x).
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Part (c)
We are given that g⁻¹(x) = 2x – 4 and need to find the corresponding function g(x).
Recall that g and g⁻¹ are inverses, so:
g(g⁻¹(x)) = x.
However, a more straightforward way is to “invert” the function g⁻¹(x). Write
y = 2x – 4
and solve for x in terms of y.
Step 1. Start with:
y = 2x – 4
Step 2. Add 4 to both sides:
y + 4 = 2x
Step 3. Divide both sides by 2:
x = (y + 4)/2
Now, reinterpret this equation. Since we began with y = g⁻¹(x) and ended with x in terms of y, the inverse of g⁻¹ is the function g. Renaming y back as the variable x, we get:
g(x) = (x + 4)/2.
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Final Answers:
a) Restrict the domain of f to x ≥ 0.
b) p⁻¹(x) = log₍₁/₂₎(x).
c) g(x) = (x + 4)/2.
Answered by UpStudy AI and reviewed by a Professional Tutor
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Explain
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Simplify this solution