Question

Galeraa que entende muito bem a Matematika... Me ajudem! Por Favor

Answer 1

 $a)\;x^2-121\neq0\Longrightarrow x^2\neq121\Longrightarrow x\neq\pm\sqrt{121}\Longrightarrow x\neq\pm11\\\\ D(f)=]-\infty,-11[U]-11,11[U]11,+\infty[$



$b)\;-x+8>0\Longrightarrow-x>-8\Longrightarrow x<8\\\\ D(f)=]-\infty,8[$



$c)\;x-1\geq 0\Longrightarrow x\geq1\\\\ D(f)=[1,+\infty[$



$d)\;\Delta\geq0\Longrightarrow b^2-4\cdot a\cdot c\geq0\Longrightarrow(-4)^2-4\cdot1\cdot3\geq0\Longrightarrow16-12\geq0\\\\\Longrightarrow16\geq12\;(\text{Verdade})\\\\ D(f)=\mathbb{R}$