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

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