log(x)16=1/log(16)x log(x)x=1
euatia devine
3/log(16)x-4log(16)x=1
log(16)x= y
ecuatia devine
3/y-4y=1
-4y²-y+3=0
4y²+y-3=0
y1=-1
y2=3/4
log(16)x=-1 => x=16^(-1)=1/16
log(16)x=3/4 x=16^(3/4)=[2^4]^(3/4)=2^3=8
_________________________
EX6 x-2≥0
4^√x-2=2^2*√x-2)
2^√x-2)=y y>0
Faci substitutia
y²+16=10y
y²-10y+16=0
REzolvi ecuatia retii numai solutiile pozitive si revii la variabila x
Ultimyul exercitiu
√(x-1)+√(x-2)+2=0
fiecare radical e un numar pozitiv 2 este tot nr, strict pozitiv. deci suma numerelor este strict pozitiva deci≠0
