Thread: Finding polynomials

Hello, I cant figure this problem out for the life of me. Could someone help me?

Find the polynomial P(x) of degree 4 with integer coefficients, and zeroes and 3 with 3, a zero of multiplicity of 2.



Thanks in advance...

Originally Posted by Godzilla

Hello, I cant figure this problem out for the life of me. Could someone help me?

Find the polynomial P(x) of degree 4 with integer coefficients, and zeroes and 3 with 3, a zero of multiplicity of 2.

Zeros are, therefore, 3-2i, 3+2i, 3, and 3.



or

can someone show me how to factor that? I am confused because of the (3-2i) and (3+2i)? Thanks!!

This polynomial:

Originally Posted by Haversine

is actually a result of this factorization:

Originally Posted by Haversine

That is, if I know the roots are A, B, C, and D, I just set up a series of polynomial factors (x - A)(x - B)(x - C)(x - D).

There's nothing special about the (x - 3 + 2i) factor, for instance. All it's saying is that I want a term that equals zero when "3 - 2i" is substituted for x.

The other imaginary term pops in there because the complex conjugate will always be a root.

The whole point is that is from the product (x-3+2i)(x-3- 2i)(x-3)(x-3). For this problem, at least, it is not a matter of "factoring" but of "multiplying"!

As far as (x-(3- 2i))(x-(3+2i))= (x-3+2i)(x-3-2i) is concerned, think of it as a "product of sum and difference= difference of squares":