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Find the G.P . For which the sum of firs...

Find the G.P . For which the sum of first two terms is -4 and the fifth term is 4 times the 3rd term.

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`T_(1)+T_(2)=-4rArra+ar=-4rArra(1+r)=-4`
`T_(5)=4.T_(3)rArrar^(4)=4ar^(2)rArrr^(2)=4rArrr=+-2`
when `r=2,a(1+2)=-4rArra=-(4)/(3)`
`therefore` The G.P. is `-(4)/(3),(-8)/(3),(-16)/(3)`.....
when `r=-2,a(1-2)=-4rArra(-1)=-4rArra=4`
`therefore` the G.P. is 4,-8,16,-32......
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