Question

find the 20th term of gp 4,12,36

Answer 1

Answer:

4649045868

Step-by-step explanation:

Find the 20th term of GP 4,12,36.

Common ratio, r = 12/4 = 3

r = 3

a = 4

GP: a, ar, ar², ar³... ar^(n-1)

a_n = a * r^(n-1)

a_n = 4 * 3^(n-1)

for n = 20

a_20 = 4 * 3^(20-1) = 4 * 3^19 = 4649045868

Answer 2

Answer:

4,649,045,868

Step-by-step explanation:

$r = \frac{a2}{a1} = \frac{12}{4} = 3 \\ an = a1 {r}^{n - 1} \\ an = 4 \times {3}^{n - 1}$

$a20 = 4(3) {}^{20 - 1} \\ a20 = 4( {3}^{19} ) \\ a20 = 4(1162261467) \\ a20 = 4,649,045,868$