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Mathematics 20 Online
OpenStudy (anonymous):

Find the polynomial function with roots 1, 7, and –3 of multiplicity 2.

OpenStudy (kinggeorge):

This is almost the same thing as your last problem. You just need to put in two \((x+3)\) terms. So just multiply out\[(x-1)(x-7)(x+3)(x+3)\]And you will get your polynomial.

OpenStudy (anonymous):

so just the x+3 has to be doubled?

OpenStudy (kinggeorge):

correct. Multiplicity is counting how many times you have that root.

OpenStudy (anonymous):

but the equation doesnnt single out the x+3

OpenStudy (kinggeorge):

What do you mean?

OpenStudy (anonymous):

it says of 1 7 and -3 not just -3

OpenStudy (kinggeorge):

So you want a polynomial with a single root of 1, a single root of 7, and two roots of -3.

OpenStudy (anonymous):

ok. so, sofar i have (x^2+7)(x^2+9)

OpenStudy (kinggeorge):

You should be getting \[(x^2-8x+7)(x^2+6x+9)\]

OpenStudy (anonymous):

ok do i add them together?

OpenStudy (kinggeorge):

You need to multiply them together again. It's a bit of work, but good practice.

OpenStudy (anonymous):

foil?

OpenStudy (anonymous):

x^4-14x^3-32x^2+42x-9

OpenStudy (kinggeorge):

You're close, it looks like you just forgot to multiply one or two terms.\[x^4-2x^3-32x^3-30x+63\]

OpenStudy (anonymous):

is -2x to the 3rd power?

OpenStudy (kinggeorge):

Yes. Here's a larger version.\[\Large x^4-2x^3-32x^3-30x+63\]

OpenStudy (anonymous):

so -34x^3

OpenStudy (kinggeorge):

no...

OpenStudy (anonymous):

why not when u have like terms u add them together

OpenStudy (kinggeorge):

I made a typo. Good thing you noticed it. \[\Large x^4-2x^3-32x^2-30x+63\]

OpenStudy (anonymous):

lol ok.

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