The value of ∑mn=1loga2n−1bm−1(a≠0;b≠0,1) is equal to
A
mloga2mbm−1
No worries! We‘ve got your back. Try BYJU‘S free classes today!
B
loga2mbm−1
No worries! We‘ve got your back. Try BYJU‘S free classes today!
C
m2loga2mb2m−2
Right on! Give the BNAT exam to get a 100% scholarship for BYJUS courses
D
m2loga2mbm+1
No worries! We‘ve got your back. Try BYJU‘S free classes today!
Open in App
Solution
The correct option is Cm2loga2mb2m−2 Let S=∑mn=1loga2n−1bm−1 ⇒S=∑mn=1(loga2n−1−logbm−1)=loga∑mn=1(2n−1)−(m−1)logb∑mn=1 ⇒S=−m(m−1)logb+loga{2∑mn=1n−∑mn=1} ⇒S=−m(m−1)logb+loga[m(m+1)−m] ⇒S=m2[2mloga−(2m−2)logb] ⇒S=m2loga2mb2m−2 Ans: C