wiz-icon
MyQuestionIcon
MyQuestionIcon
1
You visited us 1 times! Enjoying our articles? Unlock Full Access!
Question

The value of x, for which the 6th term in the expansion {2log2(9x1+7)+1215log2(3x1+1)}7 is 84, is equal to

A
4
No worries! We‘ve got your back. Try BYJU‘S free classes today!
B
3
No worries! We‘ve got your back. Try BYJU‘S free classes today!
C
2
No worries! We‘ve got your back. Try BYJU‘S free classes today!
D
1
Right on! Give the BNAT exam to get a 100% scholarship for BYJUS courses
Open in App
Solution

The correct option is D 1
alogbx=xlogba
2log2(9x1+7)=(9x1+7)log22=9x1+7
215log2(3x1+1)=(3x1+1)1/5

Tr+1=7Cr(9x1+7)7r×((3x1+1)1/5)r

T6=84
7C5(9x1+7)75×((3x1+1)1/5)5=84

21×(32x2+7)3x1+1=84
(3x)29+7=43(3x)+4

Let 3x=t
t212t+27=0
(t9)(t3)=0t=9,3
3x=9,3
or, x=2,1

flag
Suggest Corrections
thumbs-up
4
Join BYJU'S Learning Program
similar_icon
Related Videos
thumbnail
lock
General Term
MATHEMATICS
Watch in App
Join BYJU'S Learning Program
CrossIcon