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8x-3-6x-1-0-Solves-equation-x-1-x-2-




Question Number 11661 by @ANTARES_VY last updated on 29/Mar/17
8x^3 −6x+1=0.  Solves...  equation  x_1 =?     x_2 =?
$$\mathrm{8}\boldsymbol{\mathrm{x}}^{\mathrm{3}} −\mathrm{6}\boldsymbol{\mathrm{x}}+\mathrm{1}=\mathrm{0}. \\ $$$$\boldsymbol{\mathrm{Solves}}…\:\:\boldsymbol{\mathrm{equation}} \\ $$$$\boldsymbol{\mathrm{x}}_{\mathrm{1}} =?\:\:\:\:\:\boldsymbol{\mathrm{x}}_{\mathrm{2}} =? \\ $$
Answered by Joel576 last updated on 29/Mar/17
8x^3  − 6x + 2 = 0  ⇒ (x + 1)(8x^2  − 8x + 2) = 0  ⇒ x + 1 = 0     or    8x^2  − 8x + 2 = 0     • x + 1 = 0      x = −1  • 2(4x^2  − 4x + 1) = 0     (2x − 1)^2  = 0      x = (1/2)
$$\mathrm{8}{x}^{\mathrm{3}} \:−\:\mathrm{6}{x}\:+\:\mathrm{2}\:=\:\mathrm{0} \\ $$$$\Rightarrow\:\left({x}\:+\:\mathrm{1}\right)\left(\mathrm{8}{x}^{\mathrm{2}} \:−\:\mathrm{8}{x}\:+\:\mathrm{2}\right)\:=\:\mathrm{0} \\ $$$$\Rightarrow\:{x}\:+\:\mathrm{1}\:=\:\mathrm{0}\:\:\:\:\:\mathrm{or}\:\:\:\:\mathrm{8}{x}^{\mathrm{2}} \:−\:\mathrm{8}{x}\:+\:\mathrm{2}\:=\:\mathrm{0}\:\:\: \\ $$$$\bullet\:{x}\:+\:\mathrm{1}\:=\:\mathrm{0} \\ $$$$\:\:\:\:{x}\:=\:−\mathrm{1} \\ $$$$\bullet\:\mathrm{2}\left(\mathrm{4}{x}^{\mathrm{2}} \:−\:\mathrm{4}{x}\:+\:\mathrm{1}\right)\:=\:\mathrm{0} \\ $$$$\:\:\:\left(\mathrm{2}{x}\:−\:\mathrm{1}\right)^{\mathrm{2}} \:=\:\mathrm{0} \\ $$$$\:\:\:\:{x}\:=\:\frac{\mathrm{1}}{\mathrm{2}} \\ $$
Commented by @ANTARES_VY last updated on 29/Mar/17
?????
$$????? \\ $$
Commented by @ANTARES_VY last updated on 29/Mar/17
?????
$$????? \\ $$
Commented by @ANTARES_VY last updated on 29/Mar/17
?????
$$????? \\ $$
Commented by Joel576 last updated on 30/Mar/17
Hmm, before that you wrote  8x^3  − 6x + 2 = 0
$$\mathrm{Hmm},\:\mathrm{before}\:\mathrm{that}\:\mathrm{you}\:\mathrm{wrote} \\ $$$$\mathrm{8}{x}^{\mathrm{3}} \:−\:\mathrm{6}{x}\:+\:\mathrm{2}\:=\:\mathrm{0} \\ $$

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