Răspuns:
[tex]x=\frac{a,b(c)+b,c(a)+c,a(b)}{a+b+c} =\frac{\frac{abc-abx}{90}+\frac{bca-bc}{90}+\frac{cab-ca}{90}}{a+b+c} =\\=\frac{abc-bc+bca-ca+cab-ab}{90(a+b+c)} =\frac{100a+100b+100c}{90(a+b+c)} =\\=\frac{100(a+b+c)}{90(a+b+c)} =\frac{10}{9}[/tex]
[tex]9x=9\frac{10}{9} =10[/tex] ∈ 10
Explicație pas cu pas:
