$\"\"$

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The equation is $\"\"$ .

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Find the number of posible real zeros and turning points.

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Consider the equation $\"\"$ .

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The degree of the function is $\"\"$ ,hence the function have at most four real zeros and three turning poins.

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Find all the real zeros by factorize the function.

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Factorise the function $\"\"$ by equating $\"\"$ .

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$\"\"$

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$\"\"$

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$\"\"$ and $\"\"$ .

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There fore $\"\"$ and $\"\"$

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Hence the four real zeros are $\"\"$ , $\"\"$ , $\"\"$ and $\"\"$ .

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$\"\"$

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The degree of the function is $\"\"$ ,hence the function have at most four real zeros and three turning points.

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The four real zeros are $\"\"$ , $\"\"$ , $\"\"$ and $\"\"$ .