How i cant i use Distributive property on a foil equation ?

Question

This is the 1 of 5 problems

41. (x+1)(x+2)

plz. help me out here.... i need tooo know...how exactly i supposed to use distributive property ! and plz. provide a reasons. my math coach likes exact reasoning, if anybody doesn't have one, it all ends in detention.

Thanks.

Answer 1

The FOIL method is just a short-cut method for distributing.

If you had:

2( x + 1 )

You would do:

2( x ) + 2 ( 1 )

Do the same thing here--except instead of two, you have an algebraic expression.

——————————————————————————————————————

(x+1)(x+2)

= (x+1)(x) + (x+1)(2)

Now distribute again:

= (x)(x)+(1)(x) + (x)(2)+(1)(2)

= x² + x + 2x + 2

= x² + 3x + 2