The function is
.
If
is a rational zero, then
is a factor of
and
is a factor of
.
Here,
and
.
Write the possible value of
in simplest form.
and
.
Make a table and test some possible rational zeroes:
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Observe the table:
\Since
, there is a zero at
.
The depressed polynomial is
.
The quadratic function is
.
(Quadratic formula)
(Substitute
and
)
(Simplify)
(Add and simplify)
and
(Separate two roots)
and
(Simplify) \ \
There is three real roots are
,
and
.
The zeroes of the functions are
and
.