wat is (X+10) (x-1)

Hi Aziz,

I know the foil method is widely taught but I am not so keen on it because it cannot be extended to other problems.  eg (x+y+z)(4-x+2y)

 

I'd prefer to look at it like this

(X+10) (x-1)=x(x-1)+10(x-1) etc

Of course your method is perfectly valid as well.

Foil: First, Outside, Inside, Last

First: x*x = x^2.

Outside: x*-1 = -x.

Inside: 10*x = 10x.

Last: 10*-1 = -10.

 

Add all the terms: x^2 - x + 10x - 10.

 

Combine "like" terms: x^2 + 9x - 10.