1) [tex] 12^{x+1}=15,logaritmam,in,baza,12: log_{12} 12^{x+1}= log_{12}15 [/tex], exponentul trece in fata si log in baza12 din 12 =1:
[tex](x+1) log_{12}12= log_{12}15,deci,x+1= log_{12}15,de,unde
x= log_{12}15-1 [/tex]=[tex] log_{12}15- log_{12}12= log_{12} \frac{15}{12} }. [/tex]
2) [tex] (\frac{2}{5}) ^{x-1}* (\frac{25}{8}) ^{x-1}= \frac{125}{64} [/tex] ⇒
[tex] (\frac{2*25}{5*8}) ^{x-1}= \frac{125}{64},deci, (\frac{5}{4} )^{x-1}= (\frac{5}{4}) ^{3},adica,x-1=3,sau x=4. [/tex]
