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find a G.P for which sum of the first two terms is -4 and the fifth term is 4 times the third term
Given that a+ ar = -4
 =>a(1+r) = -4 ........(i)
and ar4 = 4ar2
 => r2 = 4
ie, r = ±2
from (i), a(1±2)=-4
ie, 3a= -4 or -a = -4
ie, a = -4/3       a = 4
Hence the G.P is -2, -8 , -32, . . .