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

In the expansion of (1+ax)n,nϵN,the coefficient of x and x2 are 8 and 24 respectively,then

A
a=2,n=4
Right on! Give the BNAT exam to get a 100% scholarship for BYJUS courses
B
a=4,n=2
No worries! We‘ve got your back. Try BYJU‘S free classes today!
C
a=2,n=6
No worries! We‘ve got your back. Try BYJU‘S free classes today!
D
a=2,n=4
No worries! We‘ve got your back. Try BYJU‘S free classes today!
Open in App
Solution

The correct option is A a=2,n=4
T3=nC2a2x2=24
T1=nC1ax=8
Taking the ratio we get
nC2axn=3
(n1)ax2=3
Since we are only taking the coefficients, we get
a(n1)=6
a=6(n1)
Substituting in the equation of T1 ,we get
n(6n1)=8
6n=8n8
2n=8
n=4
Hence a=2.

flag
Suggest Corrections
thumbs-up
0
Join BYJU'S Learning Program
similar_icon
Related Videos
thumbnail
lock
Binomial Coefficients
MATHEMATICS
Watch in App
Join BYJU'S Learning Program
CrossIcon