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Werse of \( y=a x^{-2} \) Given the function \( f(x)=x^{2} \) 5.1 Determine \( f^{-1}(x) \). 5.2 Draw the graph of \( f^{-1}(x) \). 5.3 Explain why \( f^{-1}(x) \) will not be a function? 5.4 Explain how you will restrict the domain of \( f(x) \) to ensure that \( f^{-1}(x) \) wil be a function.

Ask by Nichols Murray. in South Africa
Feb 18,2025

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Answer

To make \( f^{-1}(x) \) a function, restrict \( f(x) = x^2 \) to \( x \geq 0 \).

Solution

Let's solve the problem step by step. ### 5.1 Determine \( f^{-1}(x) \) The function given is \( f(x) = x^2 \). To find the inverse function \( f^{-1}(x) \), we follow these steps: 1. **Replace \( f(x) \) with \( y \)**: \[ y = x^2 \] 2. **Swap \( x \) and \( y \)**: \[ x = y^2 \] 3. **Solve for \( y \)**: \[ y = \sqrt{x} \quad \text{or} \quad y = -\sqrt{x} \] Thus, the inverse function can be expressed as: \[ f^{-1}(x) = \sqrt{x} \quad \text{and} \quad f^{-1}(x) = -\sqrt{x} \] However, since we need a single-valued function, we will choose one branch. Typically, we take the positive branch: \[ f^{-1}(x) = \sqrt{x} \] ### 5.2 Draw the graph of \( f^{-1}(x) \) To graph \( f^{-1}(x) = \sqrt{x} \), we can plot points for various values of \( x \): - For \( x = 0 \), \( f^{-1}(0) = 0 \) - For \( x = 1 \), \( f^{-1}(1) = 1 \) - For \( x = 4 \), \( f^{-1}(4) = 2 \) - For \( x = 9 \), \( f^{-1}(9) = 3 \) The graph of \( f^{-1}(x) = \sqrt{x} \) is a curve that starts at the origin (0,0) and rises to the right. ### 5.3 Explain why \( f^{-1}(x) \) will not be a function? The function \( f(x) = x^2 \) is not one-to-one because for any positive \( y \), there are two values of \( x \) (one positive and one negative) that yield the same \( y \). For example: - \( f(2) = 4 \) - \( f(-2) = 4 \) Thus, when we try to find the inverse, we end up with two outputs for a single input, which violates the definition of a function (which states that each input must correspond to exactly one output). Therefore, \( f^{-1}(x) \) is not a function unless we restrict the domain of \( f(x) \). ### 5.4 Explain how you will restrict the domain of \( f(x) \) to ensure that \( f^{-1}(x) \) will be a function. To ensure that \( f^{-1}(x) \) is a function, we can restrict the domain of \( f(x) = x^2 \) to non-negative values. This means we will only consider \( x \geq 0 \). By restricting the domain to \( [0, \infty) \), we ensure that each output \( y \) corresponds to exactly one input \( x \). Thus, the inverse function \( f^{-1}(x) = \sqrt{x} \) will be a valid function, as it will only take non-negative values of \( x \) and produce non-negative outputs. In summary: - The restricted domain of \( f(x) \) is \( [0, \infty) \). - The inverse function \( f^{-1}(x) = \sqrt{x} \) is now a valid function.

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To find the inverse function, \( f(x) = x^{2} \), we switch x and y and solve for y: 1. Start with \( x = y^2 \). 2. Rearranging gives \( y = \sqrt{x} \) or \( y = -\sqrt{x} \). Both \( \sqrt{x} \) and \( -\sqrt{x} \) would typically be solutions, but that leads us to the conclusion for 5.3! The function \( f^{-1}(x) \) will not be a function because it would fail the vertical line test; for every positive \( x \), there are two corresponding \( y \) values: one positive (the square root) and one negative (the negative square root). To ensure that \( f^{-1}(x) \) is a function (5.4), you can restrict the domain of \( f(x) \) to non-negative numbers, i.e., \( x \geq 0 \). This way, the inverse \( f^{-1}(x) = \sqrt{x} \) becomes a single valued function, allowing you to express it clearly and maintain the property of being a function!

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