Question

A={x apartine de N*| 2(x-1) mai mic decat 10 -x}
A=?​

Answer 1

$A=\{x \in N^* \mid 2(x-1)<10-x\} \\ 2x-2<10-x \\ 2x+x<10+2 \\ 3x<12 \\ x<4 \\ \Rightarrow x \in (-\infty, \ 4) \\ x \in N^* \\ \Rightarrow \boxed{A=\{1, \ 2, \ 3\}}$