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Algebra

Cool goIITian

Joined:	28 Dec 2007
Post:	76

28 Mar 2008 02:04:37 IST

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318

say true or false...

None

if a,b,c are in AP
b,c,d are in HP
a,b,c,d are not equal to zero

then a:b=c:d

the answer is true...i even did it but its too long so i want to do it in a very short way..any methods?

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Comments (2)

pinnacle

Hot goIITian

Joined: 16 Aug 2007

Posts: 176

28 Mar 2008 02:16:54 IST

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2b= a+c....(1)

c=2bd/[b+d]
bc+dc= 2bd
from (1)
bc+ dc= ad+cd
implies
bc=ad
= a/b= c/d

siddharth raghuraman

Cool goIITian

Joined: 28 Dec 2007

Posts: 76

28 Mar 2008 02:28:03 IST

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hey cool!

i got one more method...

c=2bd/b+d
=>c/d=2b/b+d
=>c/d=a+c/b+d (as a+c=2b)
=>c/d=a/b (as p/q=r/s=p+r/q+s)

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