Respostas

2014-05-19T12:33:01-03:00
 a) 2x^2-128=0 \\  \\ 2x^2=128 \\  \\ x^2= \frac{128}{2}  \\  \\ x^2=64 \\  \\ x= \sqrt{64} \\  \\ x'=8 \>\>\>\>\>\>\>\>\>\>x"=-8
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b)3x^2+15=123 \\  \\ 3x^2=123-15 \\  \\ 3x^2=108 \\  \\ x^2= \frac{108}{3}  \\  \\ x^2=36 \\  \\ x= \sqrt{36}  \\  \\ x'=6\>\>\>\>\>\>\>\>\>\>x"=-6
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c)4x^2-57=-21 \\  \\ 4x^2=-21+57 \\  \\ 4x^2=36 \\  \\ x^2= \frac{36}{4}  \\  \\ x^2=9 \\  \\ x= \sqrt{9}  \\  \\ x'=3\>\>\>\>\>\>\>\>\>\>x"=-3
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