Thread: ok, how do you know when to group these?

1. ok, how do you know when to group these?

ok thanks to mr fantastic i know pretty much how to work these problems but there is still one small area im being confused with however

for example, if the problem was like this

3q^2 + 14q + 11

i'd then need a set of integers that's sum is 14 and product is 33

the answer to that is 3 and 11.

which one comes first though when you bring the problem down? How do you know which one comes first? for example would you group 11 or 3 with 3q^2?

thanks

2. Originally Posted by formex
ok thanks to mr fantastic i know pretty much how to work these problems but there is still one small area im being confused with however

for example, if the problem was like this

3q^2 + 14q + 11

i'd then need a set of integers that's sum is 14 and product is 33

the answer to that is 3 and 11.

which one comes first though when you bring the problem down? How do you know which one comes first? for example would you group 11 or 3 with 3q^2?

thanks
$3q^2 + 3q + 11q + 11 = 3q(q + 1) + 11 (q + 1) = (q + 1)(3q + 11)$.

$3q^2 + 11q + 3q + 11 = q(3q + 11) + 1(3q + 11) = (3q + 11)(q + 1)$.

Do you think it matters which one comes first ....?

3. Originally Posted by mr fantastic
$3q^2 + 3q + 11q + 11 = 3q(q + 1) + 11 (q + 1) = (q + 1)(3q + 11)$.

$3q^2 + 11q + 3q + 11 = q(3q + 11) + 1(3q + 11) = (3q + 11)(q + 1)$.

Do you think it matters which one comes first ....?
hmm guess it doesn't. the 2nd formula i had wrong where you put q as the divisor i couldnt find anything to go as the divisor but i get it now