# Use zeros to write a polynomial function

Since we are looking for a degree 4 polynomial, and now have four zeros, we have all four factors. The other zero will have a multiplicity of 2 because the factor is squared.

### Finding polynomial equations with given zeros calculator

Let us set each factor equal to 0, and then construct the original quadratic function absent its stretching factor. Since we are looking for a degree 4 polynomial, and now have four zeros, we have all four factors. So, why go on about this? We will also use these in a later example. Using the Fundamental Theorem of Algebra Now that we can find rational zeros for a polynomial function, we will look at a theorem that discusses the number of complex zeros of a polynomial function. This theorem forms the foundation for solving polynomial equations. Authored by: Abramson, Jay et al.. To do this we simply solve the following equation. The factor theorem leads to the following fact. So we can shorten our list. Write the polynomial as the product of and the quadratic quotient. If possible, factor the quadratic. We can use the Division Algorithm to write the polynomial as the product of the divisor and the quotient: We can factor the quadratic factor to write the polynomial as By the Factor Theorem, the zeros of are —2, 3, and 5. Sections: Finding quadratics from their zeroes , Finding polynomials from a list of values How about if they give you more than just one or two roots?

This example leads us to several nice facts about polynomials. Now we apply the Fundamental Theorem of Algebra to the third-degree polynomial quotient. This fact is easy enough to verify directly.

Those require a little more work than this, but they can be done in the same manner. Finding the Zeros of Polynomial Functions The Rational Zero Theorem helps us to narrow down the list of possible rational zeros for a polynomial function.

Authored by: Abramson, Jay et al. This tells us that the function must have 1 positive real zero. Be sure to include both positive and negative candidates. Real numbers are also complex numbers.

If possible, continue until the quotient is a quadratic. When we first looked at the zero factor property we saw that it said that if the product of two terms was zero then one of the terms had to be zero to start off with.

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