x∈\(\left\{{}\begin{matrix}\\\end{matrix}\right.-1,0,1}\)

5.(x + 4)+38=123

5.(x + 4) =123-38

5.(x + 4) =85

x + 4 =85:5

x + 4 =17

x =17-4

x =13

/là dấu j

1000;2000;3000;4000;5000

B=(3+3³+3⁵)+(3⁷⁺3⁹+3¹¹)...(3²⁵+3²⁷+3²⁹)

B=273+3⁶(3+3³+3⁵)...+3²⁴(3+3³+3⁵)

B=273+3⁶.273...3²⁴.273

B=273.(3⁶....3²⁴)\(⋮\)273

\(\rightarrow\)B\(⋮\)273