#### lindsayvickroy

##### New member

- Joined
- Jul 17, 2005

- Messages
- 5

P(X) is a Polynomial of degree 4 with real coefficents and roots 5, -4, and 3+i. Find P(X).

I've gotten to (x-5)(x+4)(x-3-i)(x-3+i) but I need a little help from there.

Please help me! :?

- Thread starter lindsayvickroy
- Start date

- Joined
- Jul 17, 2005

- Messages
- 5

P(X) is a Polynomial of degree 4 with real coefficents and roots 5, -4, and 3+i. Find P(X).

I've gotten to (x-5)(x+4)(x-3-i)(x-3+i) but I need a little help from there.

Please help me! :?

- Joined
- Jul 17, 2005

- Messages
- 5

- Joined
- Feb 4, 2004

- Messages
- 15,945

- Joined
- Apr 12, 2005

- Messages
- 9,990

Remember how to multiply large numbers? Just match each digit from one with each digit from the other. It is the same, here. 3 in one and 3 in the other, you should have nine multiplications to track down.

Here's a way to split it up into three sets of three.

(x<SUP>2</SUP>-6x+10)*(x<SUP>2</SUP>-x-20)

x<SUP>2</SUP>*(x<SUP>2</SUP>-x-20) - 6*(x<SUP>2</SUP>-x-20) + 10*(x<SUP>2</SUP>-x-20)

Keep going...