Question 19: Ask the function \(y = -x ⁴ + 2x ² + 2\) to be inverse on which of the following intervals?

\(\begin{array}{l} TXĐ:\,D =\mathbb{R} \\ y = f(x) = – {x^4} + 2{x^2} + 2\\ \Rightarrow f ‘(x) = – 4{x^3} + 4x\\ f'(x) = 0 \Leftrightarrow – 4{x^3} + 4x = 0\\ \Leftrightarrow \left[\begin{array}{l}x=0\\x=-1\\x=1\end{array}\right\end{array}\)

Variation table:

Based on the variable table, determine the above inverse function (1, 2)

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