Question

Find the product?

`(a-9)^2`

Answer 1

`a^2-18a+81`

Explanation:

`(a-9)^2=(a-9)(a-9)`

`"each term in the second factor is multiplied by each"`
`"term in the first factor"`

`rArr(color(red)(a-9))(a-9)`

`=color(red)(a)(a-9)color(red)(-9)(a-9)larrcolor(blue)"distribute"`

`=(color(red)(a)xxa)+(color(red)(a)xx-9)+(color(red)(-9)xxa)+(color(red)(-9)xx-9)`

`=a^2-9a-9a+81larrcolor(blue)"collect like terms"`

`=a^2-18a+81`