$\"\"$

The equation is $\"\"$ .

Find the number of posible real zeros and turning points.

Consider the equation $\"\"$ .

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

Find all the real zeros by factorize the function.

Factorise the function $\"\"$ , substitute $\"\"$ .

$\"\"$

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

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

$\"\"$

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

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