设f(x)={log3(x^2+t),x=0,且f(1)=6,求f(f(-2))的值

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设f(x)={log3(x^2+t),x=0,且f(1)=6,求f(f(-2))的值设f(x)={log3(x^2+t),x=0,且f(1)=6,求f(f(-2))的值设f(x)={log3(x^2+

设f(x)={log3(x^2+t),x=0,且f(1)=6,求f(f(-2))的值
设f(x)={log3(x^2+t),x=0,且f(1)=6,求f(f(-2))的值

设f(x)={log3(x^2+t),x=0,且f(1)=6,求f(f(-2))的值
∵1>0,∴f(1)=log3(1+t)=6,→(1+t)=3^6→t=728
∵-2<0,∴f(-2)=2*(1+t)^(-2)=2*729^(-2)=2/(729^2)>0
∴f(f(-2))=log3(4/(729^4)+728)=log3((4+728*729^4)/729^4)
=log3(4+728*729^4)-l0g(729^4)
=30-4*6=6