1.2 Lösning 12a

$$\begin{align} 8\,x^2 + 7\,x - 1 & = 0 \\ x^2 + {7\over 8}\,x - {1\over 8} & = 0 \\ x_{1,2} & = - {7\over 16} \pm \sqrt{{49\over 256} + {32\over 256}}\\ x_{1,2} & = - {7\over 16} \pm \sqrt{81 \over 256} \\ x_{1,2} & = - {7\over 16} \pm {9\over 16} \\ x_1 & = {1\over 8} \\ x_2 & = - 1 \end{align}$$