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

The sum of the first tern and the fifth term of an ascending A.P. is 26 and the product. of the second term by the fourth term is 160. And the sum of the first seven terms of this AP.

A
110
No worries! We‘ve got your back. Try BYJU‘S free classes today!
B
114
No worries! We‘ve got your back. Try BYJU‘S free classes today!
C
112
Right on! Give the BNAT exam to get a 100% scholarship for BYJUS courses
D
116
No worries! We‘ve got your back. Try BYJU‘S free classes today!
Open in App
Solution

The correct option is C 112
Let the five terms of the A.P. be a2d,ad,a,a+d,a+2d.
Sum of the first and fifth terms is (a2d)+(a+2d)=2a
2a=26
a=13
Product of second and fourth terms is (ad)(a+d)=a2d2
a2d2=160
169d2=160
d2=9
It is an ascending A.P. and hence d takes positive values. d=3
Sum of n terms in an A.P is Sn=n2(2a+(n1)d)
Here the first term is a2d
Sum of seven terms=S=72(2(132(3))+(71)(3))
S=112
Option C is correct.

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