How do you find the product of #(r+1)(r-2)#?

1 Answer
Oct 10, 2016

Answer:

#r^2-r-2#

Explanation:

F.O.I.L.
- First
- Outer
- Inner
- Last

FOIL is just a way of factoring

So, start out by multiplying the First terms together in each set of parenthesis
#rxxr=r^2#

Outer: multiply the outer most terms in each set of parenthesis
#rxx-2=-2r#

Inner: multiply the inner terms of the set of parenthesis
#1xxr=r#

Last: multiply the last terms of each set of parenthesis together
#1xx-2=-2#

Altogether, the equation would look like:
#r^2-2r+r-2#

(I just broke it down so that it was easier to see each step)

Next, combine like terms, which would be #-2r# and #r#
#-2r+r=-r#

And the final equation looks like:
#r^2-r-2#