Question

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

Answer 1

Answer:

7 terms

Step-by-step explanation:

Given :

To find the numbeer of terms in the G.P when,

1 + 4 + 16 + 64 + ... = 5461

Solution :

We know that,

Sum of first n terms of a G.P,

$S_n = a (\frac{r^n - 1}{r - 1})$,

where n is the number of terms,

a is the first term, $a = 1$

r is the common difference, $\frac{a_2}{a_1} = \frac{4}{1} = 4$

Hence,

$5461 = 1(\frac{4^n - 1}{4 - 1} )$

$5461 = \frac{4^n - 1}{3}$

$5461 \times 3=4^n - 1$

$16383=4^n - 1$

$16384=4^n$

$4^7=4^n$ ⇒ $n=7$

Answer 2

Answer:

thanx

Step-by-step explanation:

hope you like it.