Respostas

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2014-08-07T13:02:12-03:00
A)
z^{2}=7z \\  \frac{z^{2}}{z} = \frac{7z}{z}  \\  z=7
B)
2z^{2}-16z-20=0 eq. do segundo grau - Resolver pela forma de Bascara
z= \frac{-b+ \sqrt{b^{2}-4ac}}{2a}   \frac{-(-16)+ \sqrt{(-16)^{2}-4(2)(-20)}}{2(2)} \\   \frac{16+ \sqrt{416}}{4} \\ z_{1} = -1,099  \\ z_{2}=9,099
C)
5z^{2}=-20z \\ \frac{5z^{2}}{z} = \frac{-20z}{z} \\  z=\frac{-20}{5}  \\ z=-4
D)
-2z^{2}=42z \\ \frac{2z^{2}}{z} = \frac{-42z}{z} \\ 2z=-42 \\ z= \frac{-42}{2}  \\ z=-21
4 4 4