How would I factor this -.-

Question

alones · Answer

a^2 - a - 20

thephysicsman · Answer

ask yourself this: what numbers added together will give you -1 that are both factors of 20?

random231 · Answer

^thats not actually the right way to factorize but still you are right

thephysicsman · Answer

one step at a time

alones · Answer

a(a−1)?

thephysicsman · Answer

the product of 4 and 5 = 20 

(a   4)(a     5)

alones · Answer

Oh wait i got this but it's wrong (a+4)(a−5)

thephysicsman · Answer

(a+4)(a-5) 

a^2-5a+4a-20

alones · Answer

Daaamn!1! I dont' know :3

random231 · Answer

a way that you can solve this is equating this with 0 and finding the roots of the resulting quadratic equation. :)

thephysicsman · Answer

@AloneS wolfram-alpha is a good site to help out with problems like this

alones · Answer

I did use that wiht some others to ..but it's all shows the same answer ghh

random231 · Answer

uhh how can that be? the roots of a^2-a-20 is -4 and 5

alones · Answer

I don't knwo it say so..ask my tutor xP

thephysicsman · Answer

your tutor is wrong

thephysicsman · Answer

I checked the answer on wolfram alpha

alones · Answer

K i'll go wiht your guys

random231 · Answer

what did your tutor say?
did he say the answer (a+4)(a-5) is wrong or the method is wrong?

alones · Answer

no this they saidi have to fctor completely and then place the factors in the proper location and they gave the hint 4 is at the ninth plaze /:
so i'm sitting there and trying to focua..no ideas

random231 · Answer

oh!

alones · Answer

DAANG!!The right answer was..(a-5)(a+4)20