ivy20000 ivy20000
  • 25-03-2014
  • Mathematics
contestada

16x²-81=0 solve the following quadratic equation

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deathstrike001
deathstrike001 deathstrike001
  • 25-03-2014
16x^2-81=0
(4x-9)(4x+9)
x=9/4 or x=-9/4
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Аноним Аноним
  • 29-03-2014
[tex]16x^2-81=0\\\\(4x)^2-9^2=0\\\\(4x-9)(4x+9)=0\iff4x-9=0\ \vee\ 4x+9=0\\\\4x=9\ \vee\ 4x=-9\\\\x=\frac{9}{4}\ \vee\ x=-\frac{9}{4}[/tex]


[tex]or\\\\16x^2-81=0\\\\16x^2=81\ \ \ \ /:16\\\\x^2=\frac{81}{16}\\\\x=\pm\sqrt\frac{81}{16}\\\\x=-\frac{\sqrt{81}}{\sqrt{16}}\ \vee\ x=\frac{\sqrt{81}}{\sqrt{16}}\\\\x=-\frac{9}{4}\ \vee\ x=\frac{9}{4}[/tex]
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