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## anonymous one year ago 24. 2c/c-4 - 2/1=4/c+5 I know the answer is supposed to be c=-14 but I'm not really sure what the LCD is

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1. anonymous

$\frac{ 2c }{ c-4 }-2=\frac{ 4 }{ c+5 }$

2. Vocaloid

LCD = least common denominator = (c-4)*(c+5)

3. anonymous

I don't understand how that is the LCD, can you please explain?

4. anonymous

@Vocaloid are you still online? I really need help, sorry

5. Vocaloid

the denominator of the first term is (c-4), correct? the denominator of 2 is 1 the denominator of the third term is (c+5) multiply these together to find the LCD (c-4)*(c+5)*1

6. anonymous

Okay, so then I have to multiply the other terms by that? Like: $(c-4*c+5) \frac{ 2c }{c-4 }-(c-4*c+5)2=(c-4*c+5)\frac{ 4 }{ c+5 }$ Is this correct?

7. Vocaloid

you need to multiply each term by the quantity that will make the denominator equal to (c-4)*(c+5)*1 for example, the first term is 2c/(c-4). since we already have (c-4) in the denominator, we have to multiply by (c+5)/(c+5) to make the denominator equal to (c+5)*(c-4)

8. Vocaloid

|dw:1437776145191:dw|

9. Vocaloid

|dw:1437776222377:dw|

10. Vocaloid

|dw:1437776306510:dw|

11. Vocaloid

since all the denominators are the same now, we can cancel out the denominators and look at the numerators only now (c+5)*2c - 2(c-4)(c+5) = 4*(c-4) and now we can solve for c

12. anonymous

Oh, okay, I see what you're saying sort of So multiplied that would all be $2c^{2}+10c-2c+8-2c-10c=4c-16$ so i combine like terms and then I just solve for x?

13. Vocaloid

yes

14. radar

Double check your work. There is an error on the left of the equal sign. The c^2 term should of disappeared, plus there may be other errors.

15. anonymous

@Vocaloid thank you so much for helping!! @radar was I supposed to cancel out the top c in 2c/c-4 along with cancelling the c-4?

16. radar

After the combining in the numerator your fractions should appear as:|dw:1437783584881:dw|

17. radar

|dw:1437783743735:dw|

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