Question

Carter writes the expression for the area of a deck with a width of r + 4 and a length or r - 5. He made an error when using the distributive property in the work shown. What was Carters error?
(r + 4)(r - 5)
r^2 + 4r - 5r + 20
r^2 - r + 20

Answer 1

He didn’t combine the -5r + 4r correctly and also he didn’t multiply 4 and -5 correctly.

if you can show your work. use
F O I L method
first
outer
inner
last.

r • r = r^2

r • -5 = -5r

r• 4 = 4r

4• -5 = -20.


the final equation is


R^2 + r -20