\ \
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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The depressed polynomial is
.
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The depressed polynomial is
.
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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 five real roots are
,
,
,
and
.
The zeroes of the function are
and
.