Question

how many terms of the gp 1+4+16+64+…… must be added to get sum equal ti 5461​

Answer 1

a=1,r=4,

sum =a(r^n --1)/r--1

=>5461=1×(4^n. --1)/3

16383=4^n--1

4^n=16384

(2)^2n=(128)²

(2)^2n=(2)¹⁴

2n=14

n=7