1. P.3B Polynomials and Special Factoring
Ex. 5 Cube of Binomial
(3x + 2)2 =
(3x)3 + 3(3x)2(2) + 3(3x)(2)2 + (2)3
27x3 + 54x2 + 36x + 8

2. Ex. 7 An open box is made by cutting from the corners
of a piece of metal that is 16 inches by 20 inches, as
shown. The edge of each cut-out square is x inches.
Find the volume of the box when x = 1, x = 2 and x = 3.
So we get (x)(20 – 2x)(16 – 2x)
16 – 2x
Which is 320x – 72x2 + 4x3
20 – 2x
320(1) – 72(1)2 + 4(1)3 =
252 cu. in.
320(2) – 72(2)2 + 4(2)3 =
384 cu. in. x
320(3) – 72(3)2 + 4(3)3 =
420 cu. in.
16 – 2x
20 – 2x