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a1+a1.q =4 (1)
a1.q^2 -a1=8 (2)
(1)/(2)
(1+q)/(q^2-1) = 1/2
q^2 -1 = 2+2q
q^2-2q -3=0
(q-3)(q+1)=0
q=3 or -1 (rej)
from (1)
a1+a1.q =4
a1+3a1 =4
a1=1
a1.q^2 -a1=8 (2)
(1)/(2)
(1+q)/(q^2-1) = 1/2
q^2 -1 = 2+2q
q^2-2q -3=0
(q-3)(q+1)=0
q=3 or -1 (rej)
from (1)
a1+a1.q =4
a1+3a1 =4
a1=1
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