How do you multiply $(9x + 8)(9x + 3)$ ?

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Answer 1 · 2016-09-04T15:19:05

$81x^2+99x+24$

Consider: $color(blue)((9x+8)color(brown)((9x+3))$

Multiply everything inside the right hand side (RHS) bracket by everything in the left hand side (LHS) bracket. Giving:

Notice that the + from $+8$ follows the 8

$color(brown)(color(blue)(9x)(9x+3)color(white)(.......) color(blue)(+8)(9x+3))$

$81x^2+27xcolor(white)(......) +72x+24$

$81x^2+99x+24$

How do you multiply (9x + 8)(9x + 3)(9x + 8)(9x + 3)?