SOLUTION: find each product (y^2-7y+5)(y^2-y-3) i don't undertnd

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Question 840408: find each product
(y^2-7y+5)(y^2-y-3)

i don't undertnd
Answer by josgarithmetic(39623) About Me  (Show Source):
You can put this solution on YOUR website!
This is exactly the same as for either regular decimal numbers or whole numbers. You COULD use the distributive property and carefully keep track what you are multiplying and what you already did; or you can arrange this in a lattice form and multiply that way, and in this case, it will be more comfortable.


_________y^2___________-7y___________5
-
y^2______
-
-y_______
-
-3_______


FILL-IN the cells:

_________y^2___________-7y___________5
-
y^2______y^4__________-7y^3_________5y^2
-
-y_______-y^3_________7y^2_________-5y
-
-3_______-3y^2________21y_________-15

Look along the positively sloping diagonals to find the like-terms.
Product is y%5E4-y%5E3-7y%5E3-3y%5E3%2B7y%5E2%2B5y%5E2%2B21y-5y-15
highlight%28y%5E4-11y%5E3%2B12y%5E2%2B16y-15%29