1.6a Lösning 12b

\[\begin{array}{rcl} \left|\,{5 \over x} + x\,\right| & < & 6 \\ \left|\,{5 + x^2 \over x} \,\right| & < & 6 \\ {|5 + x^2| \over |x|} & < & 6 & | \;\; \cdot |x| \\ |5 + x^2| & < & 6\,|x| \qquad & &: \;\text{Skriv 4 och 17 som 10-potenser}\\ \end{array}\]

\[\begin{align} \sqrt{{\color{White}{[}}\!6\,x + 10} \, + \, 1 & = x & | \;\; -1 \\ \sqrt{{\color{White}{[}}\!6\,x + 10} & = x - 1 & | \; (\;\;\;)^2 \\ 6\,x + 10 & = (x - 1)^2 \\ 6\,x + 10 & = x^2 - 2 x + 1 \qquad\qquad & | - 10 \\ 6\,x & = x^2 - 2 x - 9 \qquad\qquad & | - 6 x \\ 0 & = x^2 - 8 x - 9 \\ \end{align}\]