Before diving into the vertical method, let's go through one more example of the horizontal method. Multiply (x\(\small\mathsf{ ^2 }\) – 2)(2x\(\small\mathsf{ ^2 }\) + x – 1) on your own. Then click below to check your work.
= 2x\(\small\mathsf{ ^4 }\) + x\(\small\mathsf{ ^3 }\) – x\(\small\mathsf{ ^2 }\) – 4x\(\small\mathsf{ ^2 }\) – 2x + 2
= 2x\(\small\mathsf{ ^4 }\) + x\(\small\mathsf{ ^3 }\) – 5x\(\small\mathsf{ ^2 }\) – 2x + 2
Try the problem below for more practice with the horizontal method.
Question
(x + 4)(x\(\small\mathsf{ ^2 }\) + 3x + 9)
x • x\(\small\mathsf{ ^2 }\) + x • 3x + x • 9 + 4 • x\(\small\mathsf{ ^2 }\) + 4 • 3x + 4 • 9
x\(\small\mathsf{ ^3 }\) +3x\(\small\mathsf{ ^2 }\) + 9x + 4x\(\small\mathsf{ ^2 }\) + 12x + 36
x\(\small\mathsf{ ^3 }\) + 7x\(\small\mathsf{ ^2 }\) + 21x + 36
x\(\small\mathsf{ ^3 }\) +3x\(\small\mathsf{ ^2 }\) + 9x + 4x\(\small\mathsf{ ^2 }\) + 12x + 36
x\(\small\mathsf{ ^3 }\) + 7x\(\small\mathsf{ ^2 }\) + 21x + 36
