Rezolvarile exercitiilor lor 2) si 3) le gasesti in fisierul atasat.
Pe celelalte exerciti le voi rezolva aici.
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[tex]\displaystyle\bf\\1)\\Se~da:\\lg3=a\\Se~cere:\\lg900=?\\\\Folosim~formula:~~~lg(a\cdot b)=lg(a)+lg(b)\\\\lg900=\\=lg(9\times100)=\\=lg9+lg100=\\=lg(3^2)+lg10^2=\\=2lg3+2lg10=\\=\boxed{\bf2a+2}\\\\\\4)\\lg12+lg15-lg18=lg\frac{12\times15}{18}=lg\frac{180}{18}=lg10=\boxed{\bf1}\\\\\\5)\\2013-2=2011\\2011:4=502~rest~3\\A~3-a~zecimala~din~perioada~(8923)~este~~2.\\\implies~A~2013-a~zecimala~din~numarul~3,\!\!12(8923)~este~~\boxed{\bf2}[/tex]
