A function \(f\) is such that \(f(x) = \frac{15}{2x+3}\) for \(0 \leq x \leq 6\).
Find an expression for \(f^{-1}(x)\), and state the domain and range of \(f^{-1}\).
Solution
Let \(y = \frac{15}{2x+3}\).
Rearrange to solve for \(x\):
\(2x + 3 = \frac{15}{y}\)
\(2x = \frac{15}{y} - 3\)
\(x = \frac{15 - 3y}{2y}\)
Thus, \(f^{-1}(x) = \frac{15 - 3x}{2x}\).
For the range of \(f^{-1}\), since \(0 \leq x \leq 6\) for \(f(x)\), the range of \(f^{-1}\) is \(0 \leq f^{-1}(x) \leq 6\).
For the domain of \(f^{-1}\), solve \(0 \leq \frac{15}{2x+3} \leq 6\) for \(x\):
\(1 \leq x \leq 5\).
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