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Mathematics 8 Online
OpenStudy (anonymous):

Can Someone Teach Me How to Factor? I'll Invite you to my iPad Contest.. :)

OpenStudy (amistre64):

teach? dunno.... I can explain tho :)

OpenStudy (anonymous):

it's like this:\[2x^2+3x-3=0\] kind of like foiling.

OpenStudy (amistre64):

Yes, the opposite of foiling, the unfoiling if you will...

OpenStudy (anonymous):

the easy way?

OpenStudy (amistre64):

what I do is assume that I can factor and set it up like this: if there is a number in the front (that 2 there) use it for "a" in the following: (x ()/a) (x ()/a)

OpenStudy (anonymous):

what's () ?

OpenStudy (amistre64):

It is just something to fill in with a number we find.

OpenStudy (amistre64):

(x ()/2) (x ()/2) is what I got so far. you with me?

OpenStudy (anonymous):

the signs are still invisible, right?

OpenStudy (amistre64):

yep, the equation actually tells us how to fill those in, but they are not important in step one.

OpenStudy (anonymous):

ok. i'm understanding it a bit more

OpenStudy (amistre64):

How is the last term inthe equation made? by addition or multiplication?

OpenStudy (anonymous):

i converted sin of theta into X

OpenStudy (amistre64):

X is not important yet; but that little (-3) at the end of your equation...how did it get there? was it (a)(b) = -3? or (a)+(b) = (-3)

OpenStudy (anonymous):

the full equation from the textbook was: \[2\sin ^2 \theta+3\cos \theta-3=0\]

OpenStudy (amistre64):

we will keep that in mind for later; but fer now, we need to KNOW how that (-3) got created. Was it by multiplication or addition?

OpenStudy (anonymous):

it was from the textbook. it asks me to find the exact values in degrees

OpenStudy (amistre64):

let me ask it this way; in order to "FOIL" to factors together to create the equation . The last term ther , that (-3) was made by some process. Was it by adding or multiplying.... think how to "unFOIL" this.

OpenStudy (amistre64):

(x + y)(x + y) = xx +xy +xy +yy (x + y)(x + y) = x^2 +2xy +y^2 Is that last term there, that (y^2) made by adding or by multiply 2 numbers together?

OpenStudy (anonymous):

umm.. it's plus and minus

OpenStudy (amistre64):

y^2 = y+y ? or y^2 = y(y) ? (-3) = 1 + (-3)? or (-3) = (1)(-3)?

OpenStudy (anonymous):

by unfoiling it, i get: \[(2\sin \theta- number)(\sin \theta + number)=0\]

OpenStudy (amistre64):

I should probably clarify this: Do you want to know HOW to factor? or How to use the quadratic formula to find the answers?

OpenStudy (anonymous):

yea.

OpenStudy (anonymous):

i need to know how to factor the fastest way

OpenStudy (amistre64):

the fastest way is to use the quadratic formula to find the solutions to a quadratic(a squared) equation.

OpenStudy (amistre64):

quadratic is a fancy name for: the exponent value of "x" in this equation is a "2".

OpenStudy (anonymous):

i meant i want to know how to factor. i'm left with those two numbers. which one should i pick.

OpenStudy (amistre64):

Ill step you through how I do it :) which works if there are only inegers involved; otherwise, use the quad formula.

OpenStudy (anonymous):

allrights~

OpenStudy (amistre64):

step1: multiply the first number and the last number to get your actual value that you need to factor to get 2 numbers. In this equation I would that would be: (2)(3) = 6. That is step 1.

OpenStudy (anonymous):

ok

OpenStudy (amistre64):

step 2: setup your factoring into (x....()/a)(x.....()/a). For this equation that would be this: (x ( /2)) (x ( /2)) That is step 2:

OpenStudy (amistre64):

step 3: look at the sign of the last term. In this case we have a (-3). If the sign is (+); I either need (+)(+) OR (-)(-) If the sign is (-) I need (+)(-) this sign of the last number tells me what I am going to use. In your case (-3) tells me that I am going to use (+)(-) step three is done.

OpenStudy (amistre64):

step 4: What is the sign of the middle term? In this case we have (+3) This sign tells me that whichever numbers I pick; the largest one is this sign. If it is a (-) sign on the middle term; the largest number is (-) If it is a (+) sign on the middle term; the largest number is (+) In your case here; the sign of the middle term (+3) is (+); my biggest number will be positive. Step 4 is done.

OpenStudy (amistre64):

step 5: fill in what I already know: (x + ( /2)) (x - (/2)) step 5 is done.

OpenStudy (amistre64):

to clarify; in step 5 I used what I knew from YOUR equation that we are using. ok?

OpenStudy (anonymous):

ok. i was wondering how to find the numbers. the rest is fine.

OpenStudy (amistre64):

step 6: take the number we got back in step 1, or simply wait til now to get it :) remember we muliplied the first and last terms. (first)(last) (2)(3) = 6 we factor (6) to get our numbers. 1,6 2,3 Those are all I can get out of it... None of these will subtract to get (+3) 6-1 = 5 3-2 = 1 There is no way to use this method to factor your ORIGINAL equation. because we cannot get 2 number that work to fill in our missing stuff. End here and do quad formula.

OpenStudy (anonymous):

ahh, i get it now. that's the answer i want. thanks heres the ipad link: http://on.fb.me/gJlBGl

OpenStudy (amistre64):

there are going to be square roots involved; or maybe even no answer. But this method works for any integer value that can be found :)

OpenStudy (anonymous):

thanks!

OpenStudy (amistre64):

whats an iPad contest?

OpenStudy (anonymous):

kinda like a prize award?

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