Log₅(9-2)+log₅125=5 <=> Log₅7+3=5 <=> Log₅7=2 - это не верно ))
Если же Log₅(9-x)+log₅125=5 <=> Log₅(9-x)+3=5 <=> Log₅(9-x)=2 <=> Log₅(9-x)=2*Log₅5 <=> Log₅(9-x)=Log₅25 <=> 9-x=25 <=> x=-16.
1. cos3x=1/2
cos3x=+-arccos1/2+2pk,kcZ
cos3x= +-p/3+2pk, kcZ
cosx=+-p/3+2pk/3,kcZ
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ОТВЕТ: - 2 ; - 0,5
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