Ask
your own question, for FREE!
Mathematics
7 Online
OpenStudy ($oumya):
help plz...
Join the QuestionCove community and study together with friends!
Sign Up
OpenStudy ($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
Join the QuestionCove community and study together with friends!
Sign Up
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
Join the QuestionCove community and study together with friends!
Sign Up
OpenStudy (ikram002p):
have no clue what the rest would be , sry
Can't find your answer?
Make a FREE account and ask your own questions, OR help others and earn volunteer hours!
Join our real-time social learning platform and learn together with your friends!
Latest Questions
clllaaaaaire:
CLOSED
2 weeks ago
0 Replies
0 Medals