Thread: rational expressions

ok ive got like 50 questions here @_@ but im guna post one to start out to see if maybe that mistake will fix the rest as well..

http://aycu22.webshots.com/image/113...3916155_rs.jpg

Tell me what im doing wrong?

Thanks so much

bumper?

another problem is...

5/x-2 + 6

book's answer is 6x-7/x-2

....
and i got

6x+3/x-2

Originally Posted by Cait

ok ive got like 50 questions here @_@ but im guna post one to start out to see if maybe that mistake will fix the rest as well..

http://aycu22.webshots.com/image/113...3916155_rs.jpg

Tell me what im doing wrong?

Thanks so much

you are incorrect, you forgot to keep the x - 2 in brackets

5/(x-2) + 6
= 5/(x - 2) + 6*(x - 2)/(x - 2) ...................here you put 6x - 2, that's wrong, it's 6(x - 2)
= 5/(x - 2) + (6x - 12)/(x - 2)
= (6x - 7)/(x - 2)

Originally Posted by Cait

ok ive got like 50 questions here @_@ but im guna post one to start out to see if maybe that mistake will fix the rest as well..

http://aycu22.webshots.com/image/113...3916155_rs.jpg

Tell me what im doing wrong?

Thanks so much

For the first one:
x/(x^2 - 1) - 7/(1 - x^2)

= x/(x^2 - 1) + 7/(x^2 - 1)

= (x + 7)/(x^2 - 1)

The second one:
5/(x - 2) + 6

= 5/(x - 2) + 6(x - 2)/(x - 2)

= 5/(x - 2) + (6x - 12)/(x - 2)

= (5 + 6x - 12)/(x - 2)

= (6x - 7)/(x - 2)

-Dan

Originally Posted by Cait

ok ive got like 50 questions here @_@ but im guna post one to start out to see if maybe that mistake will fix the rest as well..

http://aycu22.webshots.com/image/113...3916155_rs.jpg

Tell me what im doing wrong?

Thanks so much

here:

Originally Posted by Jhevon

here:

Factoring a simple -1 from the second denominator does wonders, doesn't it?

-Dan

Originally Posted by topsquark

Factoring a simple -1 from the second denominator does wonders, doesn't it?

-Dan

that it does. i waited until i combined fractions before i took out the -1 however, but we could have done it as easy in the beginning

Omg i am retarded...

with that picture i posted the problem to #21.. and the work to #25.



Ugh this still doesnt explain..


#21 is..

x/x^2-1 - 7/1-x^2

and THEIR answer is 1/x-2.

and /I/ and YOU guys got x+7/x^2-1



Is the book wrong????????

ok here's another..

5x/x+2 - 3x-4/x+2


The books answer is 2. Just plain 2.


MY answer i get is 2x+4/x+2.



So what'd i do wrong here??

or is the answers in this book just sucking today? lol

Originally Posted by Cait

Omg i am retarded...

with that picture i posted the problem to #21.. and the work to #25.



Ugh this still doesnt explain..


#21 is..

x/x^2-1 - 7/1-x^2

and THEIR answer is 1/x-2.

and /I/ and YOU guys got x+7/x^2-1



Is the book wrong????????

yes, the book is wrong. or maybe you looked up the answer to a different prob by accident.

you can see that the answer is wrong for yourself.

plug in for instance, x = 3 into x/x^2-1 - 7/1-x^2, you get a different answer from when you plug in x = 3 into 1/(x - 2)

Originally Posted by Cait

ok here's another..

5x/x+2 - 3x-4/x+2


The books answer is 2. Just plain 2.


MY answer i get is 2x+4/x+2.



So what'd i do wrong here??

or is the answers in this book just sucking today? lol

you are correct, but you should simplify. your answer is 2 as well

(2x + 4)/(x + 2) = 2(x + 2)/(x + 2) = 2

Ok thanks you guys are lifesavers!

Now lets see what problems i have with the next section! XD but that will be for another post....