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So I have the task to prove that (c+1)/(c^2-1)-(c+1)/(1-c) can be simplified to (c+2)/(c-1)and I have simplified the first term to 1/(c-1) and I am then left with 

-(c+1)/(-c+1)+1/(c-1) and to my understanding will i factor the term "-c+1" to -(c-1), but what I don't get is how I can then remove the - infront of (c+1)/(-c+1) and end up with equal denominators to combine the fractions

 Sep 3, 2015

Best Answer 

 #1
avatar+223 
+5

I´m not sure how to explain it but I´ll give you my solution:

(c+1)/(c^2-1)-(c+1)/(1-c)=

 

= 1/(c-1) - (c+1)/(1-c)                                                              (conjugates)

= (1-c)/(c-1)(1-c)  - (c+1)(c-1)/(c-1)(1-c)                                 (common denominators)

= (1-c)+(-(c-1)(c+1))/ -(c-1)(c-1)                                               the red text is replaced with 1 due to divison

= (1+ c+1)/(c-1)

=(c+2)/(c-1)     

 

 

VSB

 

Good luck, if i have been unclear about something, ask me or someone else here:)

 Sep 3, 2015
 #1
avatar+223 
+5
Best Answer

I´m not sure how to explain it but I´ll give you my solution:

(c+1)/(c^2-1)-(c+1)/(1-c)=

 

= 1/(c-1) - (c+1)/(1-c)                                                              (conjugates)

= (1-c)/(c-1)(1-c)  - (c+1)(c-1)/(c-1)(1-c)                                 (common denominators)

= (1-c)+(-(c-1)(c+1))/ -(c-1)(c-1)                                               the red text is replaced with 1 due to divison

= (1+ c+1)/(c-1)

=(c+2)/(c-1)     

 

 

VSB

 

Good luck, if i have been unclear about something, ask me or someone else here:)

Headingnorth Sep 3, 2015
 #2
avatar+128577 
+5

(c+1)/(c^2-1)-(c+1)/(1-c) =

 

1/ (c - 1)  - (c + 1)/ (1 - c)           factor the negative out of the second denominator

 

1/(c -1) (+) - (c + 1)/ [- (c -1)]     notice that the negatives in the numerator and denominator "cancel' with each other

 

And we're left with

 

1/(c -1) + (c + 1)/(c -1)  =

 

(1 + c + 1) / (c -1)  =

 

(c + 2)/(c -1) 

 

Factoring out a negative is a good "trick" in some cases  !!!

 

 

cool cool cool

 Sep 4, 2015

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