How do you factor $9 - 6a - 24a^2$ ?

Question

7345 views around the world

You can reuse this answer
Creative Commons License

Answer 1 · 2015-05-26T20:52:17

Given $9-6a-24a^2$

Extract the common constant factor of 3
$=3(3-2a-8a^2)$

Examine factors of 3 and -8
Remembering $(p+qa)(r+sa) = pq + (ps+qr)a +(qs)a^2$
where in this case $pq = 3$ , $ps+qr = -2$ , and $qs= -8$

Note that $3xx1 = 3$
and $4xx(-2) = -8$
and $3xx(-2)+(4)xx1 = -2$

So we can continue to factor:
$=3(3+4a)(1-2a)$

How do you factor 9 - 6a - 24a^29 - 6a - 24a^2?