Respostas

2014-05-22T21:50:48-03:00
São equações do segundo grau
Ax^2+Bx+C=0

o coeficiente A (sempre acompanha o x²)
o coeficiente B (sempre acompanha o x)
e o coeficiente C ( sempre está sozinho) 

utilize a formula d bhaskara pra resolver
\boxed{\boxed{\frac{-b\pm \sqrt{b^2-4*a*c} }{2*a} }}
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2x^2+7x+3=0

A = 2 (porque acompanha o x²)
B = 7 (porque acompanha o x)
C = 3 (é o que est sozinho)

substituindo os valores dos coeficientes na formula
\frac{-b\pm \sqrt{b^2-4*a*c} }{2*a}=\frac{-7\pm \sqrt{7^2-4*2*3} }{2*2}= \frac{-7\pm \sqrt{49-24} }{4} = \frac{-7\pm \sqrt{25} }{4} = \frac{-7\pm 5 }{4} \\\\\\\\x'= \frac{-7-5}{4} = \frac{-12}{4} =-3\\\\x'' \frac{-7+5}{2} = \frac{-2}{4} =- \frac{1}{2}
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-x^2+11x-28=0

A= -1 (porque acompanha o x²)
B = 11
C = -28
 \frac{-11\pm \sqrt{11^2-4*(-1)*(-28)} }{2*(-1)} = \frac{-11\pm \sqrt{121-112} }{-2} = \frac{-11\pm \sqrt{9} }{-2} = \frac{-11\pm3}{-2} \\\\x'= \frac{-11-3}{-2} = \frac{-14}{-2} =7\\\\x''= \frac{-11+3}{-2} = \frac{-8}{-2} =4
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2x^2+23x-39=0
A = 2
B = 23
C = -39

\frac{-23\pm \sqrt{23^2-4*2*(-39)} }{2*2} = \frac{-23\pm \sqrt{841} }{4}= \frac{-23\pm29}{y}  \\\\x'= \frac{-23- 29 }{4}  =-13\\\\x''= \frac{-23+ 29 }{4} = \frac{6}{4} = \frac{3}{2}
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6x^2+5x-1=0

acho que essa vc consegue fazer rs ...
a resposta x' = -1 .. x'' =  \frac{1}{6}
2 5 2
  • Usuário do Brainly
2014-05-22T22:17:55-03:00
2x² + 7x + 3 = 0
Δ = b² - 4 . a . c
Δ = 7² - 4 . 2 . 3
Δ = 49 - 24
Δ = 25

x = (- b ± √Δ)/2 . a
x = (- 7 ± √25)/2 . 2
x = (- 7 ± 5)/4

x' = (- 7 + 5)/4
x' = - 2/4
x' = - 1/2

x'' = (- 7 - 5)/4
x'' = - 12/4
x'' = - 3

- x² + 11x - 28 = 0
Δ = b² - 4 . a . c
Δ = 11² - 4 . (- 1) . (- 28)
Δ = 121 - 112
Δ = 9

x = (- b ± √Δ)/2 . a
x = (- 11 ± √9)/2 . (- 1)
x = (- 11 ± 3)/- 2

x' = (- 11 + 3)/- 2
x' = - 8/- 2
x' = 8/2
x' = 4

x'' = (- 11 - 3)/- 2
x'' = - 14/- 2
x'' = 14/2
x'' = 7

2x² + 23x - 39 = 0
Δ = b² - 4 . a . c
Δ = 23² - 4 . 2 . (- 39)
Δ = 529 + 312
Δ = 841

x = (- b ± √Δ)/2 . a
x = (- 23 ± √841)/2 . 2
x = (- 23 ± 29)/4

x' = (- 23 + 29)/4
x' = 6/4
x' = 3/2

x'' = (- 23 - 29)/4
x'' = - 52/4
x'' = - 13

6x² + 5x - 1 = 0
Δ = b² - 4 . a . c
Δ = 5² - 4 . 6 . (- 1)
Δ = 25 + 24
Δ = 49

x = (- b 
± √Δ)/2 . a
x = (- 5 ± √49)/2 . 6
x = (- 5 ± 7)/12

x' = (- 5 + 7)/12
x' = 2/12
x' = 1/6

x'' = (- 5 - 7)/12
x'' = - 12/12
x'' = - 1