Join the Most Relevant JEE Main 2025 Test Series & get 99+ percentile! Join Now
Search any question & find its solution
Question: Answered & Verified by Expert
Let a, b, c be the three distinct positive real numbers such that 2alogea=bclogeb and bloge2=alogec Then 6a+5bc is equal to ______.
MathematicsBasic of MathematicsJEE MainJEE Main 2023 (10 Apr Shift 1)
Solution:
2890 Upvotes Verified Answer
The correct answer is: 8

Given equation: 2alna=bclnb

lna·ln2a=lnb·lnbc

lna·ln2+lna=lnb·lnb+lnc

let lna=x, lnb=y, lnc=z, xyz

xln2+x=yy+z

xln2=y2-x2+yz ........(i)

Similarly, from second equation

ln2·lnb=lnc·lna

ln2=xzy ......(ii)

Substitute eqii in eqi,

We get,

y3-yx2+y2z=x2z

y2y+z-x2y+z=0

y2-x2y+z=0

x-yx+yy+z=0

 xyx+yy+z=0

Now x=-y, y=-z and x=z

But ln2=xzy

ln2=xx-x

ln2=-lna

=-ln 2a=12 and

y=-z

lnb=-lnc

bc=1

Now 6a+5bc=612+51=8

Hence this is the required answer.

Looking for more such questions to practice?

Download the MARKS App - The ultimate prep app for IIT JEE & NEET with chapter-wise PYQs, revision notes, formula sheets, custom tests & much more.