Question

Alguém consegue montar a conta

Answer 1

Resposta:

$x + y = - 2$

$x.y = - 8$

$x = - \frac{8}{y}$

$\frac{8}{y} + y = 2$

$- \frac{8 + {y}^{2} }{y} = - 2$

$- 8 + {y}^{2} = - 2y$

${y}^{2} + 2y - 8 = 0$

$s = \frac{ - b}{a}$

$s = - \frac{2}{1}$

$s = - 2$

$p = \frac{c}{a}$

$p = - \frac{8}{1}$

$p = - 8$

$x1 = 2 \: \: x2 = - 4$

$x = 2 \: \: y = - 4$

Answer 2

$\left \{ {{x+y=-2} \atop {xy=-8}} \right. \\\\x+y=-2\\\\x= -2-y\\\\xy=-8\\\\(-2-y)y=-8\\\\-2y-y^{2} = -8 (-1)\\\\2y+y^{2} =8\\\\y^{2}+2y+8=0 \\\\a=1 \\ b=2\\ c=8\\\\y=\frac{-b+-\sqrt{\delta}}{2a}$

Δ=$b^{2}-4ac$

Δ= 2²-4.1.8

Δ=-28(-1)

Δ= 28

$y= \frac{-2-+\sqrt{28} }{2*1} \\\\y^{'} = \frac{-2+\sqrt{28} }{2} \\\\\\y^{'} = \frac{-2+2\sqrt{7} }{2} \\\\\\y^{'} = -2\sqrt{28} \\\\y^{''} = \frac{-2-\sqrt{28} }{2} \\\\\\y^{'} = +2\sqrt{28}$