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OpenStudy (kanwal32):
If a,b,c are in AP and a^2,b^2,c^2 are in GP a<b<c and a+b+c=3/2 then value of a is
OpenStudy (kanwal32):
@ganeshie8 @ikram002p hlp
OpenStudy (kainui):
what is AP and GP?
OpenStudy (kainui):
Arithmetic and Geometric Progression?
OpenStudy (kanwal32):
Aritmetic Progression and Geometric Progession
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OpenStudy (kanwal32):
yes
OpenStudy (kanwal32):
b=1/2
OpenStudy (kanwal32):
found out
OpenStudy (kanwal32):
a??????
OpenStudy (kainui):
Ok, well if a, b, and c are in an arithmetic progression, then that means there's some quantity you can add to a to get b and to b to get c. Similarly we can set up an equation for their squares in the GP.
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OpenStudy (kanwal32):
YES
OpenStudy (kainui):
So make as many equations as you can and see if we can solve for anything.
OpenStudy (ikram002p):
well
c-b=b-a
\(c^2/b^2=b^2/a^2\)
OpenStudy (kanwal32):
yes
OpenStudy (ikram002p):
ok
c+a-2b=0
2a+2b+2c=3
\(c^2 a^2=b^4\)
\(ca=b^2\)
ok u have 3 equations with 3 variables ^
solve
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OpenStudy (kanwal32):
i have solved it this like but the answer is wrong
OpenStudy (kanwal32):
@ikram002p @Kainui @hartnn view this answer is \[\frac{ 1 }{2 }-\frac{ 1 }{ \sqrt{2} }\]
OpenStudy (kanwal32):
pls hlp
hartnn (hartnn):
ac = 1/4
a+c = 2b =1
hartnn (hartnn):
quadratic in a
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OpenStudy (kanwal32):
yes i did this
OpenStudy (kanwal32):
c=2,a=-1
hartnn (hartnn):
getting
a=b=c= 1/2 ...which are not acceptable values
OpenStudy (kanwal32):
no i got a=-1,b=1/2,c=2
hartnn (hartnn):
b^4 = (ac)^2
b^2 = +ac, b^2 =-ac
ac = -1/4
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OpenStudy (kanwal32):
yeah
hartnn (hartnn):
ac =-1/4
a+c =1/2
now you will get it
hartnn (hartnn):
a-1/(4a) = 1/2
solve
OpenStudy (aum):
I am getting the same too. a = b = c = 1/2. Satisfies all equations except they AP and GP unless a common difference of zero counts as AP and common ratio of 1 counts as GP.
OpenStudy (kanwal32):
ok so i didn't +- ok
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hartnn (hartnn):
doesn't satisfy a<b<c aum
OpenStudy (aum):
Oh, yeah. Some mistake in this problem? or a typo?
OpenStudy (kanwal32):
yes @hartnn u r cprrect @aum 1/2 is not the answer
hartnn (hartnn):
no mistake
a-1/(4a) = 1/2
did u get how i got this equation
OpenStudy (kanwal32):
yes @hartnn
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hartnn (hartnn):
solve it, its a quadratic
hartnn (hartnn):
sorry, that should be
a-1/(4a) = 1
because
a+c = 2b =1
OpenStudy (anonymous):
@hartnn is righttt..btw hartnn cud u help me out
OpenStudy (kanwal32):
i got \[4a^2-4a+1\]
hartnn (hartnn):
a+c = 2b =1
ac = -b^2 , ac = b^2
ac =b^2 is rejected because a<b<c
ac=-b^2 =-1/4
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hartnn (hartnn):
you should get
4a^2 -4a-1 =0
OpenStudy (kanwal32):
wait let me check and figyre out ny nistake
OpenStudy (kanwal32):
ok
OpenStudy (kanwal32):
i didn't reject +b^2
OpenStudy (kanwal32):
got u hartnn
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hartnn (hartnn):
4a^2 -4a-1 =0
will give you one root as your answer