Question

A={xapartine lui R|2x-1<9}

Answer 1

2x - 1 < 9 
2x < 9 + 1
2x < 10 
x < 10 :2 
x < 5 
in R , intervalul  x∈ ( - ∞ ;  5)

Answer 2

$2x - 1 \ \textless \ 9 =\ \textgreater \ 2x \ \textless \ 9 + 1 =\ \textgreater \ 2x \ \textless \ 10 =\ \textgreater \ x \ \textless \ 5$
x∈(-∞,5)