1. [tex]\overline{abc} :7=\overline{bc}~~rest ~~a[/tex]
[tex]\overline{abc}=7*\overline{bc}+a[/tex]
100a+10b+c=70b+7c+a
99a-60b-6c=0
33a-20b-2c=0
=> a =par si a<8
=> pt a=2=> b=3 si c=3
pt a=4=> b=6 si c=6
pt a=6=> b=9 si c=9
=> [tex]\overline{abc} [/tex]∈{233,466,699}
2.
2²²²+3¹¹¹ =(2¹¹¹)²+3¹¹¹
2¹¹¹+3²²²=2¹¹¹+(3¹¹¹)²
=> 2²²²+3¹¹¹<2¹¹¹+3²²²