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  • Usuário do Brainly
2014-07-09T15:38:24-03:00
A)
 x^{2} -49=0

 x^{2} =49

 x^{2} = \sqrt{49}

x'=7
x"=-7

S={-7,7}

b)
 x^{2} =1

 x^{} = \sqrt{1}

x'=1
x"=-1

S={-1,+1}

c)
2 x^{2} -50=0

2 x^{2} =50

 x^{2} = \frac{50}{2}

 x^{2} =25

 x^{} = \sqrt{25}
x'=5
x"=-5

S={-5,5}

d)
7 x^{2} -7=0

7 x^{2} =7

 x^{2} = \frac{7}{7}

 x^{2} =1

 x^{} = \sqrt{1}

x'=1
x"=-1

S={-1,1}

e)
5 x^{2} +15=0

5 x^{2} =-15

 x^{2} = \frac{-15}{3}

 x^{2} =-3

 x^{} = \sqrt{-3} ∉R

S={  }

f)
21=7 x^{2}

7 x^{2} =21

 x^{2} = \frac{21}{7}

 x^{2} =3

 x^{} = \sqrt{3}

 x^{'} = \sqrt{3}

 x^{"} =- \sqrt{3}

S={ \sqrt{3} , -\sqrt{3} }

g)
5 x^{2} +20=0

5 x^{2} =-20

 x^{2} = \frac{-20}{5}

 x^{2} =-4

 x^{} = \sqrt{-4} ∉R

S={  }

h)
7 x^{2} +2=30

7 x^{2} =30-2=28

 x^{2} = \frac{28}{7}

 x^{2} =4

 x^{} = \sqrt{4}

x'=2
x"=-2

S={-2,2}
2 5 2
tem mais ......
g)5x²+20 =0
h) 7x² +2 =30
Resolvida...completei.