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Mathematics 22 Online
OpenStudy ($oumya):

help plz...

OpenStudy ($oumya):

a,b,c in geometrical progression.. a^2+b^2+c^2=S^2 a+b+c=qS show that 1/3<q^2<3

OpenStudy ($oumya):

@ganeshie8

OpenStudy (ikram002p):

a,b,c in geometrical progression.. does that mean a b=ar c=ar^2 ?

ganeshie8 (ganeshie8):

yes

OpenStudy ($oumya):

yes @ikram002p

OpenStudy (ikram002p):

ok then \( \large a^2+a^2r^2+a^2r^4=s^2\) \( \large a^2(1+ r^2+ r^4)=s^2\) \(\large a+b+c=qs\) \(\large a+ar+ar^2=qs\) \(\large a(1+r+r^2)=qs\) \(\large a^2(1+r+r^2)^2 =q^2s^2\) thus \(\large q^2=\dfrac { a^2(1+r+r^2)^2 }{s^2} \) \(\large q^2=\dfrac { a^2(1+r+r^2)^2 }{a^2(1+ r^2+ r^4) } \) \(\large q^2=\dfrac { (1+r+r^2)^2 }{(1+ r^2+ r^4) } \)

OpenStudy (ikram002p):

mmm lets see how to go far from this

OpenStudy (ikram002p):

we know r\(\neq 0\) r\(\neq 1\) so \(0<r<1\) or \(1<r\)

OpenStudy (ikram002p):

mmm idk how to continue xD since i got \(q^2>3\) for \(r>1\) xD

OpenStudy (ikram002p):

ok ill go through this part \(0<r<1\) \(0<r^2<1\) \(0<r^4<1\) but \(0<r^4<r^2<r <1\) mmm

OpenStudy (ikram002p):

have no clue what the rest would be , sry

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