$\"\"$

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 five real zeros and four turning poins.

Find all the real zeros by factorize the function.

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

$\"\"$

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

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

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

$\"\"$

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

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