Question

Z-5=z^2-25 помогите

Answer 1

z-5=z²-25
-z²+z-5+25=0
-z²+z+20=0
z²-z-20=0

$sqrt{D} = sqrt{(-1)^2-4*(-20)} = sqrt{1+80} = sqrt{81} = 9$

x₁= $frac{1+9}{2} = frac{10}{2} = 5$

x₂= $frac{1-9}{2} = - frac{8}{2} = -4$