Question

com resolver X²+0,4x-3,2=0

Answer 1

$x^2+0,4x-3,2=0\\\\ \Delta=b^2-4\cdot a\cdot c\\ \Delta=(0,4)^2-4\cdot1\cdot(-3,2)\\ \Delta=0,16+12,8\\ \Delta=12,96\\\\ x=\dfrac{-b\pm\sqrt{\Delta}}{2a}=\dfrac{-0,4\pm\sqrt{12,96}}{2\cdot1}=\dfrac{-0,4\pm3,6}{2}\Longrightarrow\begin{cases}x_1=\frac{3,2}{2}=1,6\\x_2=\frac{-4}{2}=-2\end{cases}\\\\ S\{-2;\;1,6\}$