How do you multiply $(7x)(8x)$ ?

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Answer 1 · 2015-06-26T22:56:40

$(7x)(8x) = 56x^2$

$(7x)(8x) = (7*x)*(8*x) = 7*x*8*x = 7*8*x*x$

$= (7*8)*(x*x) = 56x^2$

using commutativity and associativity of multiplication.

That is, for any $a$ , $b$ and $c$ :

$a * b = b * a$

and

$a * (b * c) = (a * b) * c$

How do you multiply (7x)(8x) (7x)(8x) ?