Saturday, January 22, 2011

2011/006) If x > 1, y > 1, z > 1 are in G.P.

If x > 1, y > 1, z > 1 are in G.P., then 1/(1+In x), 1/(1+In y),1/(1+ In z) are in :
(A) A.P.
(B) H.P.
(C) G.P.
(D) none of these

(this is objective and should not take more than a minute)

ans is B

reason
x > 1, y > 1, z > 1 are in G.P. so ln x, ln y, ln z are in AP and >0

so 1 + ln x, and 1+ in y and 1 + ln z in AP and hence the result

3 comments:

Unknown said...

is ln natural log here ? What properties have you used . Thanks

Unknown said...

Hello sir,
Can you explain what properties have you used and is ln here natural log ?

kaliprasad said...

ln is natural log and if

x y z are in GP then

xz = y^2

so ln x + ln z = 2 ln y so
ln x , ln y, in z are in AP