# Distributive Law

• June 1st 2012, 10:08 AM
CSMajor
Distributive Law
Ok, so I'm self-teaching myself Algebra over the summer so that's one less math class I'll have to worry about and I have a question about 2 algebra problems. I'm trying to find out how exactly the author of the book I'm using got the answer to these 2 questions and it would help a lot if you could explain why the answers are the answers. I believe monomial's and polynomial's using the distributive law.

The first 2x^2y(x^2-xy+3y) and the answer in the book was 2x^4y - 2x^3y^2+6x^2y^2

The second a/2 (2a-4+3b) and the answer was a^2-2a+3ab/2
• June 1st 2012, 10:18 AM
Plato
Re: Distributive Law
Quote:

Originally Posted by CSMajor
I believe monomial's and polynomial's using the distributive law.

The first 2x^2y(x^2-xy+3y) and the answer in the book was 2x^4y - 2x^3y^2+6x^2y^2

Do you understand how $(2x^2y)(x^2)=2x^4y$ works?

Do you understand how $(2x^2y)(-xy)=-2x^3y^2$ works?

Do you understand how $(2x^2y)(3y)=6x^2y^2$ works?
• June 1st 2012, 10:46 AM
CSMajor
Re: Distributive Law
Somewhat, but not really to be honest.
• June 1st 2012, 10:56 AM
Plato
Re: Distributive Law
Quote:

Originally Posted by CSMajor
Somewhat, but not really to be honest.

Try to explain what you don't understand about each of those three.
• June 1st 2012, 11:24 AM
CSMajor
Re: Distributive Law
Well for the first and second problems I understood why you got those answers. For the third I think I understand how you got the answer, but not exactly. Unless I'm able to multiply
3y times 2x^2 to get 6x^2y^2 that way, but I didn't think that was the right way.
• June 1st 2012, 11:48 AM
Plato
Re: Distributive Law
Quote:

Originally Posted by CSMajor
I'm able to multiply 3y times 2x^2 to get 6x^2y^2 that way, but I didn't think that was the right way.

$(2x^2y)(3y)=2\cdot 3\cdot x^2\cdot y\cdot y=6x^2y^2$
• June 1st 2012, 11:58 AM
CSMajor
Re: Distributive Law
yeahhh... you made it look so much easier than I made it seem written out.