Question

How do you multiply `(9a +2) (9a^2 + a + 1)`?

Answer 1

`=color(blue)(81a^3 + 27a^2 +11a+2`

Explanation:

`color(blue)((9a+2))(9a^2+a+1)`
`=color(blue)((9a)) *(9a^2+a+1) +color(blue)((2)) . (9a^2+a+1)`

note : `color(blue)(a^m*a^n=a^(m+n)`, is the property applied to exponents of `a`

`=81a^3 +9a^2 +9a + 18a^2 +2a +2`

Adding like terms

`=color(blue)(81a^3 + 27a^2 +11a+2`