[tex] log_{7} (3- \sqrt{2} )+ log_{7}(3+ \sqrt{2} ) =[/tex]
Folosim formula [tex] log_{a}b+ log_{a} c= log_{a} (b*c)[/tex]
[tex] log_{7} (3- \sqrt{2} )(3+ \sqrt{2} )=[/tex]
Folosim formula [tex](a-b)(a+b)= a^{2}- b^{2} [/tex]
[tex] log_{7} ( 3^{2}- \sqrt{2} ^{2} } )[/tex]
[tex] log_{7} (9-2)[/tex]
[tex] log_{7} 7=1[/tex]