Identify Possible Rational Zeros:
\It is not practical to test all possible zeros of a polynomial function using only synthetic substitution.
\The Rational Zero Theorem can be used for finding the some possible zeros to test.
\The function is
.
Because the leading coefficient is
, the possible rational zeros are the intezer factors of the constant term
.
Therefore the possible rational zeros of
are
.
The function is
.
Perform the synthetic division method by testing
and
.
Since
, conclude that
is a zero of
.
Therefore,
is a rational zero.
The depressed polynomial is
.
Finding Rational Zeros :
\The depressed polynomial is
.
Find the rational zeros use the quadratic formula
.
Consider
.
Where
.
Substiute the values in the quadratic formula
.

The zeros of the depressed polynomial are
.
Therefore
and
are the two factors.
Therefore,
and
are the factors of
.
By using Factor theorem,
\When
then
is a factor of polynomial.
Factor of
.
So
has three real zeros.
Zeros are
.
The correct answer is
.