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

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Answer 1 · 2015-08-23T11:01:43

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

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

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

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

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