Question

How do you multiply `3y ^ { 2} + 6y + 5` and `y - 9` using the vertical format?

Answer 1

`3y^3-21y^2-49y -45`

Explanation:

Multiplying in vertical format is the same as long multiplication with numbers:

`" "3y^2 +6y+5`
`ul(xx" "color(blue)(y)color(red)( -9)" "larr` muliply each term by the top row
`color(blue)(3y^3+6y^2+5y`
`ul(" "color(red)(-27y^2-54y-45))" "larr` like terms under each other
`ul(3y^3-21y^2-49y -45)" "larr`add like terms