Question 43: Let the function \(y=f(x)\) have a table of variation as shown in the figure. How many extreme points does the function have?

Determination set \(D=\mathbb{R} \backslash\left\{x_{1}\right\}\) .

According to the theorem of sufficient conditions for the function to have extremes and based on the table of variation, we have the extreme points of the function as: \(x_{2} ; x_{4} ; x_{5}\)

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