Question

If sum of the GP 1, 4, 16,…….is 341, then find number of terms of the GP

Answer 1

Answer:

n=5

Step-by-step explanation:

Given that 1+4+16+..............=341

so first term a=1, r=b/a=4/1=4, r=4 s=341

so sum of gp

S= a[r^n-1]/(r-1)

put the value of a,r&s

so. 341=1[4^n-1]/(4-1)

341=[4^n-1]/3

341×3=(4^n-1)

1023=(4^n-1)

1023+1=(4^n)

1024=4^n

4^5=4^n

compare

5=n

n=5

Answer 2

Answer:

Please see the image :)

note :

a=1

r=4

n=?

(these steps were not clear when the photo was taken)