
Brandon R. answered 06/14/20
Experienced Algebra and Geometry Tutor
Hello, let's review the FOIL method to begin.
F: First (multiply the first terms in each binomial)
O: Outer (multiply the first term of the first binomial and the second terms of the second binomial)
I: Inner (multiply the two inner terms)
L: Last (multiply the second terms in each binomial)
When multiplying binomials, we use FOIL to make sure we multiply the terms in each binomial appropriately. How does this relate to your problem? Since we want to cover the total area of grass, we must find the area of the garden. What is the formula for Area?
A = length x width
Let's fill in the length and width with the expressions given to us in the problem. L = (X-5) and W = (x+2).
A = (x-5)(x+2)
Now, we have a binomial multiplication to do. We can use FOIL as shown below.
A = (x-5)(x+2) <--- F: x*x= x2 ; O: x*2= 2x ; Inner: -5*x = -5x ; Last: -5*2 = -10
A = x2 + 2x - 5x -10
Combine Like Terms: 2x - 5x = -3x
A = x2 - 3x -10