How do you multiply $(x + 3)(x - 7)$ ?

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Answer 1 · 2015-07-02T13:10:31

$=color(blue)(x^2 - 4x -21$

$color(green)( (x+3)).(x-7)$
$=color(green)( (x)).(x-7)+ color(green)((3)).(x-7)$

$= x^2 - 7x +3x -21$
$=color(blue)(x^2 - 4x -21$

How do you multiply (x + 3)(x - 7)(x + 3)(x - 7)?