Question

How do you find the product of `(d-1)(5d-4)`?

Answer 1

`=5d^2-9d+4`

Explanation:

We have 2 factors which have to be multiplied. Each part of the first bracket has to be multiplied by each part of the second bracket. This is sometimes called the FOIL rule: "Firsts, Outers, Inners, Lasts"

`(color(blue)(d)color(red)(-1))(5d-4)`

`=color(blue)(d)(5d-4)color(red)(-1)(5d-4)`

`=color(blue)(5d^2-4d)color(red)(-5d+4)" "larr` collect the like terms

`=5d^2-9d+4" "larr` this is the product.

(It is a quadratic trinomial )