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If f(1)=3 and f(n)=-2f(n-1), then f(5)=

User Ignazio
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f(n)=-2 f_(n-1) \\ f_(1) =3 \\ f(2)=-2 f_(1)=-2*(3)=-6 \\ f(3)=-2 f_(2)=-2*(-6)=12 \\ f(4)=-2 f_(3)=-2*(12)=-24 \\ f(5)=-2 f_(4)=-2*(-24)=48

and


f_(n) =3* (-2)^(n-1)
User Geny
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