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Example Questions
Example Question #21 : Finding Zeros Of A Polynomial
Consider the polynomial
Which of the following is true of the rational zeroes of ?
Hint: Think "Rational Zeroes Theorem".
The only rational zero of is .
has no rational zeroes.
has at least one rational zero, but neither nor 1 is a zero.
The only rational zeroes of are and 1.
The only rational zero of is 1.
The only rational zeroes of are and 1.
By the Rational Zeroes Theorem, any rational zeroes of a polynomial must be obtainable by dividing a factor of the constant coefficient by a factor of the leading coefficient. Since both values are equal to 1, and 1 has only 1 as a factor, this restricts the set of possible rational zeroes to the set .
Both values can be tested as follows:
1 is a zero of if and only if . An easy test for this is to add the coefficients and determine whether their sum, which is , is 0:
1 is indeed a zero.
is a zero of if and only if . An easy test for this is to add the coefficients after changing the sign of the odd-degree coefficients, and determine whether their sum, which is , is 0. However, as their are no odd-degree coefficients, the sum is the same:
is also a zero.
Example Question #263 : College Algebra
Determine the zeros of the following equation:
To determine the zeros of this equation, we will need to factorize the polynomial.
The only common factors of that will give us a middle term of negative by addition or subtraction is:
Set each binomial equal to zero and solve.
The zeros are:
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