For geometric progression find the common ratio ‘r’, and then fin

1.	For geometric progression find the common ratio ‘r’, and then find an.2, -6, 18, -54, …….
Answer» Given G.P. = 2, -6, 18, -54, ……. a = 2, r = \(\frac{a_2}{a_1}\) = \(\frac{-6}{2}\) = -3 a_n= a . r^n-1 = 2 × (-3)^n-1 ∴ r = -3; a_n = 2(-3)^n-1

For geometric progression find the common ratio ‘r’, and then find an.2, -6, 18, -54, …….

Answer»

Given G.P. = 2, -6, 18, -54, …….

a = 2, r = \(\frac{a_2}{a_1}\) = \(\frac{-6}{2}\) = -3

a_n= a . r^n-1 = 2 × (-3)^n-1

∴ r = -3; a_n = 2(-3)^n-1