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

Oct 10, 2016

${r}^{2} - r - 2$

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
$r \times r = {r}^{2}$

Outer: multiply the outer most terms in each set of parenthesis
$r \times - 2 = - 2 r$

Inner: multiply the inner terms of the set of parenthesis
$1 \times r = r$

Last: multiply the last terms of each set of parenthesis together
$1 \times - 2 = - 2$

Altogether, the equation would look like:
${r}^{2} - 2 r + r - 2$

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

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

And the final equation looks like:
${r}^{2} - r - 2$