Question

Demonstrați ca ab+ba se divide cu 11

Answer 1

[tex]\bar{ab} = 10 \cdot a + b \\ \bar{ba} = 10 \cdot b + a \\ \bar{ab}+\bar{ba}=10\cdot a + b + 10\cdot b + a = 11\cdot a +11\cdot b = 11\cdot (a+b)[/tex]