1 задание срочно плииииииииизззз

$x^{2} -4x+3=0$
$D =(-4)^2-4*1*3=16-12=4$
$x_{1} = \frac{4+2}{2} = \frac{6}{2} =3$
$x_{2} = \frac{4-2}{2} = \frac{2}{2} =1$
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$x^{2} +9x=0$
$x(x+9)=0$
$x=0$
или
$x+9=0$
$x=-9$
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$7 x^{2} -x-8=0$
$D=(-1)^2-4*7*(-8)=1+224=225$
$x_{1} = \frac{1+15}{14} = \frac{16}{14} = \frac{8}{7}$
$x_{2} = \frac{1-15}{14} = \frac{-14}{14} = -1$