How do you factor $4a^3-64a$ ?

Question

1326 views around the world

You can reuse this answer
Creative Commons License

Answer 1 · 2016-05-07T20:47:14

$4a(a-4)(a+4)$

4 is a factor of both 4 and 64

$a$ is a factor of both $4a^2" and "64a$

Factor out $4a$ giving:

$4a(a^2-16)$

But 16 is the same as $4^2$

$4a(a^2-4^2)$

'...........................................
compare to the example $y^2-z^2=(y-z)(y+z)$
'..............................................

$color(brown)(4a(a^2-4^2))color(blue)(" "->" "4a(a-4)(a+4)$

How do you factor 4a^3-64a4a^3-64a?