How do you simplify $(sqrta-4)(sqrta+4)$ ?

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Answer 1 · 2017-01-20T12:39:45

$a-16$

$(sqrta-4)(sqrta+4)$

Let's do each multiplication then add up the results:

$sqrtasqrta=a$
$sqrta(4)=4sqrta$
$(-4)sqrta=-4sqrta$
$(-4)(4)=-16$

$a+4sqrta-4sqrta-16=a-16$

How do you simplify (sqrta-4)(sqrta+4)(sqrta-4)(sqrta+4)?