1.

Which of the following are G.P. ? If they are G.P, write three more terms,4, 8, 16, ……

Answer»

Given: 4, 8, 16, …… 

where, a1 = 4; a2 = 8; a3 = 16, …… 

\(\frac{a_2}{a_1}\) = 8/4 = 2

\(\frac{a_3}{a_2}\) = 16/8 = 2

∴ r = \(\frac{a_2}{a_1}\)\(\frac{a_3}{a_2}\) = 2 

Hence 4, 8, 16, … is a G.P. 

where a = 4 and r = 2 

a4 = a . r3 = 4 × 23 = 4 × 8 = 32 

a5 = a . r4 = 4 × 24 = 4 × 16 = 64 

a6 = a . r5 = 4 × 25 = 4 × 32 = 128



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