a∈(−∞,0]a\in \left( -\infty ,0\right] a∈(−∞,0]
a∈[1.∞,]a\in \left[ 1.\infty ,\right] a∈[1.∞,]
a∈[0.1]a\in \left[ 0.1\right] a∈[0.1]
a∈(0.1]a\in \left(0.1\right] a∈(0.1]
a∈R−{0.1}a\in R -\left\{ 0.1\right \} a∈R−{0.1}