Multiplying the rational expresion. i need help!!!!

[Ashlie]

I need help understanding how to do these problems.
I need someone to go step by step for me.
Please.

4x^2y^3 * xy
x^5y^6 20x^3

and this one is a little bit difrent from the rest so maybe you could show me how to work it too.

3x^2-12 * 1
5x-10 2x+4


Thank You![/tex][/list]

 

[Denis]

4x^2y^3 * xy
x^5y^6 20x^3

Do the multiplications ; remember that x^a * x^b = x^(a+b):

4 x^2 y^3 * x y = 4 x^3 y^4

x^5 y^6 * 20 x^3 = 20 x^8 y^6

So we're now at:
4 x^3 y^4 / (20 x^8 y^6)

Simplify ; remember that x^a / x^b = x^(a-b) or 1 / x(b-a):

1 / (5 x^5 y^2)

Hope that helped.