1
You visited us 1 times! Enjoying our articles? Unlock Full Access!
Question

# If (10)9+2(11)1(10)8+3(11)2(10)7+⋯+10(11)9=k(10)9, then k is equal to

A
12110
No worries! We‘ve got your back. Try BYJU‘S free classes today!
B
441100
No worries! We‘ve got your back. Try BYJU‘S free classes today!
C
100
Right on! Give the BNAT exam to get a 100% scholarship for BYJUS courses
D
110
No worries! We‘ve got your back. Try BYJU‘S free classes today!
Open in App
Solution

## The correct option is C 100Let the sum be denoted by S then S=109+2×11×108+3×112×107+.....+10×119or,1110S=11×108+2×112×107+.........+9×119+11×119on subtracting we getS10=109+11×108+112×107+......+118×10+119−1110we can see that except the last term all the terms are in G.P with a =109 and r=1110Hence ⇒S10=109(111010−1)1110−1−1110=1010(111010−1)−1110⇒S=10×1010=100(10)9Therefore, k=100

Suggest Corrections
0
Join BYJU'S Learning Program
Related Videos
Introduction
MATHEMATICS
Watch in App
Explore more
Join BYJU'S Learning Program