How do you FOIL $(2x - 5y) ( x + y)$ ?

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Answer 1 · 2015-06-05T21:50:45

Given $(2x-5y)(x+y)$ pick out pairs of terms to multiply in the order given by FOIL:

First: $2x xx x = 2x^2$
Outside: $2x xx y = 2xy$
Inside: $-5y xx x = -5yx = -5xy$
Last: $-5y xx y = -5y^2$

Then add these all together to get:

$2x^2+2xy-5xy-5y^2 = 2x^2-3xy-5y^2$

How do you FOIL (2x - 5y) ( x + y)(2x - 5y) ( x + y)?