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Mathematics 17 Online
OpenStudy (anonymous):

Divide. Can someone please help? https://study.ashworthcollege.edu/access/content/group/38441f94-71d6-46e6-8dd7-ece73f5a6548/exam_11_files/mc009-1.jpg

OpenStudy (anonymous):

@jim_thompson5910 do you know how to do this ?

jimthompson5910 (jim_thompson5910):

The first step is to flip the second fraction and multiply so that gives you \[\Large \frac{x^2+2x+1}{x-2} \bullet \frac{x^2-4}{x^2-1}\] what's next?

OpenStudy (anonymous):

ummm i really have no idea...

jimthompson5910 (jim_thompson5910):

the next step is to factor each expression so x^2+2x+1 factors to ??

OpenStudy (anonymous):

i am not understanding :(

jimthompson5910 (jim_thompson5910):

are you able to factor x^2+2x+1

OpenStudy (anonymous):

do you set it equal to zero?

jimthompson5910 (jim_thompson5910):

have a look at this page http://www.purplemath.com/modules/factquad.htm

jimthompson5910 (jim_thompson5910):

it gives an example

OpenStudy (anonymous):

would it be (x + 1)(x + 1)?

jimthompson5910 (jim_thompson5910):

good

jimthompson5910 (jim_thompson5910):

factor x^2-4 to get ???

jimthompson5910 (jim_thompson5910):

it might help to think of x^2-4 as x^2+0x-4

OpenStudy (anonymous):

(x-2)(x+2).?

OpenStudy (anonymous):

?????????

jimthompson5910 (jim_thompson5910):

good, then x^2 - 1 factors to ???

OpenStudy (anonymous):

(x - 1)(x + 1) ???

jimthompson5910 (jim_thompson5910):

So \[\Large \frac{x^2+2x+1}{x-2} \bullet \frac{x^2-4}{x^2-1}\] turns into \[\Large \frac{(x+1)(x+1)}{x-2} \bullet \frac{(x-2)(x+2)}{(x-1)(x+1)}\]

OpenStudy (anonymous):

is that the answer ?

jimthompson5910 (jim_thompson5910):

then you do these cancellations \[\Large \frac{(x+1)(x+1)}{x-2} \bullet \frac{(x-2)(x+2)}{(x-1)(x+1)}\] \[\Large \frac{\cancel{(x+1)}(x+1)}{x-2} \bullet \frac{(x-2)(x+2)}{(x-1)\cancel{(x+1)}}\] \[\Large \frac{x+1}{x-2} \bullet \frac{(x-2)(x+2)}{x-1}\] \[\Large \frac{x+1}{\cancel{x-2}} \bullet \frac{\cancel{(x-2)}(x+2)}{x-1}\] \[\Large \frac{x+1}{1} \bullet \frac{x+2}{x-1}\] \[\Large \frac{(x+1)(x+2)}{x-1}\]

jimthompson5910 (jim_thompson5910):

The cancellations work because dividing any expression by itself is 1 (example: 5/5 = 1)

jimthompson5910 (jim_thompson5910):

Then 1*x = x, so the 1 effectively goes away

OpenStudy (anonymous):

ok

OpenStudy (anonymous):

can you help with this one ? simplify the rational expression. state any excluded values. x^2-x-6/x+2

jimthompson5910 (jim_thompson5910):

factor the numerator to get ???

OpenStudy (anonymous):

ummm (x+2) (x+2) idk this one

jimthompson5910 (jim_thompson5910):

x^2-x-6 is the same as x^2-1x-6 so you have to find two numbers that multiply to -6 AND add to -1

OpenStudy (dangerousjesse):

@jim_thompson5910 It amazes me how well you teach. Sorry to interrupt.

jimthompson5910 (jim_thompson5910):

Thank you for the compliment. It's greatly appreciated.

OpenStudy (anonymous):

A.x - 3, where x 3 B. x-2 C.1/x- 2 , where x - 2 D.x - 3, where x -2 these are the answers i can choice from and and i am think it is B? is that correct or is it C?

OpenStudy (anonymous):

wait i think i did my math wrong....

jimthompson5910 (jim_thompson5910):

what did you get when you factored x^2-1x-6

OpenStudy (anonymous):

it would be (x-3)(x-3) right?

jimthompson5910 (jim_thompson5910):

-3 times -3 = 9 we want the two numbers to multiply to -6

OpenStudy (anonymous):

(x-3)(-2)?

jimthompson5910 (jim_thompson5910):

I think you meant (x-3)(x-2)

jimthompson5910 (jim_thompson5910):

-3 times -2 = 6 again, we want -6

OpenStudy (anonymous):

i am confused?

jimthompson5910 (jim_thompson5910):

here are all of the ways to multiply to -6 -6 = -1*6 -6 = -2*3 -6 = -3*2 -6 = -6*1 which pair of factors adds to -1 ?

OpenStudy (anonymous):

-3+2= -1

jimthompson5910 (jim_thompson5910):

that -3 and +2 are then used to form the factorization of x^2-1x-6

jimthompson5910 (jim_thompson5910):

x^2-1x-6 factors to (x-3)(x+2)

jimthompson5910 (jim_thompson5910):

\[\Large \frac{x^2-x-6}{x+2}\] turns into \[\Large \frac{(x-3)(x+2)}{x+2}\] I'm sure you see what to do from here

OpenStudy (anonymous):

(x-3) but out of the answers to pick what one would it be A.x - 3, where x neq 3 B. x-2 C.1/x- 2 , where x neq - 2 D.x - 3, where x neq -2

jimthompson5910 (jim_thompson5910):

keep in mind that you cannot divide by zero

jimthompson5910 (jim_thompson5910):

so you have to make sure the denominator isn't zero the denominator is zero when x = -2 since x+2 = 0 x = -2 so we must add the restriction that \(\Large x \neq -2\) to avoid division by zero.

jimthompson5910 (jim_thompson5910):

x can be 3 since that doesn't make the denominator zero

OpenStudy (anonymous):

so it would be D ?

jimthompson5910 (jim_thompson5910):

yes

OpenStudy (anonymous):

ok thank you!

jimthompson5910 (jim_thompson5910):

np

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