How would i factor a simple question like 3a^2 + 2
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jimthompson5910 (jim_thompson5910):
3a^2 and 2 have nothing in common (except 1), so that cannot be factored
OpenStudy (anonymous):
i just still dont understand....oh boy..
OpenStudy (anonymous):
what about one like 3a^2 + 9?
jimthompson5910 (jim_thompson5910):
the GCF of 3 and 2 is 1
there are no variables common between them, which is why the GCF of 3a^2 and 2 is 1
jimthompson5910 (jim_thompson5910):
3a^2 and 9 have a 3 in common though
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jimthompson5910 (jim_thompson5910):
so you can factor out 3 to get
3a^2 + 9 = 3(a^2 + 3)
OpenStudy (anonymous):
Oh i see how that one works now. thanks. and for the one i just asked....what does it mean by putting it in factored form?
jimthompson5910 (jim_thompson5910):
it just means factor it as much as possible
jimthompson5910 (jim_thompson5910):
example: if you factor the number 10, then you would get 2*5
jimthompson5910 (jim_thompson5910):
2*5 is the factored form
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OpenStudy (anonymous):
like how would i factor that one out...?
jimthompson5910 (jim_thompson5910):
to factor 3a^2 + 9 completely, you would get
3a^2 + 9 = 3(a^2 + 3)
and that's all you can do
jimthompson5910 (jim_thompson5910):
3(a^2 + 3) is the factored form
OpenStudy (anonymous):
OHHHHHH, THANK YOU SO MUCH. you are a hero
jimthompson5910 (jim_thompson5910):
you're welcome, glad it's making sense now
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OpenStudy (anonymous):
:D
OpenStudy (anonymous):
wait wait...
OpenStudy (anonymous):
what if in the directions it said x^2 + 3x + 2
OpenStudy (anonymous):
to factor that expression? would that work the same way?
jimthompson5910 (jim_thompson5910):
sort of...but you would use a different trick now
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jimthompson5910 (jim_thompson5910):
the last term is 2
the middle coefficient is 3
jimthompson5910 (jim_thompson5910):
you want to find two numbers that multiply to 2 (last term) AND add to 3 (middle coefficient) at the same time
jimthompson5910 (jim_thompson5910):
which two numbers do this?
OpenStudy (anonymous):
well... 1 x 2 = 2 and 2 + 1 = 3
so.... 2?
OpenStudy (anonymous):
i think......
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jimthompson5910 (jim_thompson5910):
good, so the two numbers are 1 and 2
jimthompson5910 (jim_thompson5910):
which means x^2 + 3x + 2 factors to (x + 1)(x + 2)
jimthompson5910 (jim_thompson5910):
you can check by expanding (x + 1)(x + 2) out and you'll get x^2 + 3x + 2 back again
OpenStudy (anonymous):
oh yay! I see how that works. what if their was a number in front of the x
jimthompson5910 (jim_thompson5910):
then it would be slightly different, but you would use the same basic idea
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jimthompson5910 (jim_thompson5910):
do you have anything in mind?
OpenStudy (anonymous):
as in 4n^2 - 20n +25
jimthompson5910 (jim_thompson5910):
ok first you would multiply 4 (the first coefficient) and 25 (last term) to get
4*25 = 100
jimthompson5910 (jim_thompson5910):
now you must find two numbers that
a) multiply to 100
AND
b) add to -20
at the same time
OpenStudy (anonymous):
uhhh
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OpenStudy (anonymous):
i understand how to do it now but i cant figure out what goes into each
jimthompson5910 (jim_thompson5910):
how about -1 and -100
-1 + (-100) = -101
no that doesn't work
jimthompson5910 (jim_thompson5910):
-2 and -50 ?
-2 + (-50) = -52
nope, doesn't work either
jimthompson5910 (jim_thompson5910):
-4 and -25?
-4 + (-25) = -29
still no
jimthompson5910 (jim_thompson5910):
-5 and -20 ?
-5 + (-20) = -25
no, but we're getting closer
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jimthompson5910 (jim_thompson5910):
-10 and -10?
-10 + (-10) = -20
which works
OpenStudy (anonymous):
yeah i see that
jimthompson5910 (jim_thompson5910):
so we break up the -20n into -10n-10n to get this
4n^2 - 10n - 10n +25
jimthompson5910 (jim_thompson5910):
then you would factor by grouping
OpenStudy (anonymous):
like terms?
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jimthompson5910 (jim_thompson5910):
first group the terms into pairs
4n^2 - 10n - 10n +25
(4n^2 - 10n) + (-10n +25)
jimthompson5910 (jim_thompson5910):
then factor each group separately
jimthompson5910 (jim_thompson5910):
(4n^2 - 10n) + (-10n +25)
2n(2n - 5) + (-10n +25)
2n(2n - 5) - 5(2n - 5)
see what to do next?
OpenStudy (anonymous):
kinda ish
jimthompson5910 (jim_thompson5910):
what do you think the next step is
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OpenStudy (anonymous):
distributing
jimthompson5910 (jim_thompson5910):
yes in a way, but in reverse
jimthompson5910 (jim_thompson5910):
notice we have the common term of (2n-5)
OpenStudy (anonymous):
factoring outt.... i think
jimthompson5910 (jim_thompson5910):
so we factor that out to get this
(2n - 5)(2n - 5)
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OpenStudy (anonymous):
ohhh i see
jimthompson5910 (jim_thompson5910):
if we had
x(2n-5) + y(2n-5)
we would factor out the (2n-5) to get
(x+y)(2n-5)
OpenStudy (anonymous):
oh i think i get it thank you!!!! gold star for you!
jimthompson5910 (jim_thompson5910):
ok glad it's all making sense, you'll be a pro in no time and you'll have to change your user name lol
OpenStudy (anonymous):
haha!! i just never grasp the concepts with my teacher!! haha hopefully i can change it though!!
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jimthompson5910 (jim_thompson5910):
you can definitely change it, just keep practicing and you'll be fine
OpenStudy (anonymous):
will do!!!! haha
jimthompson5910 (jim_thompson5910):
lol good, and also try to get things in terms of your own language
no sense in repeating the same thing over and over again if you don't know how to translate
OpenStudy (anonymous):
thats so true! i dont even know most terms! its crazy! thanks for the advice:)
jimthompson5910 (jim_thompson5910):
you're welcome, you might do well to write them on flash cards or something. That usually helps me
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OpenStudy (anonymous):
yeah ill do that forsure!! and jusst wondering, are you in highschool?
jimthompson5910 (jim_thompson5910):
no I'm in college learning to become a teacher
OpenStudy (anonymous):
ohhh man! thats really cool! hope you are successful!!