• Matéria: Matemática
  • Autor: dkiwilson
  • Perguntado 9 anos atrás

(a) Se x > 1 determine o valor da expressão 1 - |x-|1-x|| eliminando os módulos.
(b) Sabendo que x < 0, elimine os módulos de |x-|x-1||.


Respostas

respondido por: Lukyo
1
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(a) Se \mathsf{x&gt;1}, então

\mathsf{|1-x|=|x-1|=x-1}\\\\ \mathsf{\Rightarrow~~\big|x-|1-x|\big|=\big|x-(x-1)\big|=\big|1\big|=1}\\\\ \mathsf{\Rightarrow~~1-\big|x-|1-x|\big|=1-1=0\qquad\quad\checkmark}


\therefore~~\mathsf{1-\big|x-|1-x|\big|=0\qquad para~x&gt;1.}

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(b) Se \mathsf{x&lt;0}, então

\mathsf{x&lt;0&lt;1~~\Rightarrow~~x&lt;1~~\Rightarrow~~|x-1|=1-x}\\\\ \mathsf{\Rightarrow~~\big|x-|x-1|\big|=\big|x-(1-x)\big|=\big|2x-1\big|\qquad(i)}\\\\\\ \mathsf{\big|2x-1\big|}=\left\{\! \begin{array}{rl} \mathsf{2x-1,}&amp;\mathsf{se~2x-1\ge 0}\\\\ \mathsf{-(2x-1),}&amp;\mathsf{se~2x-1&lt;0} \end{array} \right.\qquad\quad\mathsf{~e~~x&lt;0}\\\\\\\\ \mathsf{\big|2x-1\big|}=\left\{\! \begin{array}{rl} \mathsf{2x-1,}&amp;\mathsf{se~x\ge \frac{1}{2}}\\\\ \mathsf{1-2x,}&amp;\mathsf{se~x&lt;\frac{1}{2}} \end{array} \right.\qquad\quad\mathsf{~e~~x&lt;0}


\mathsf{\big|2x-1\big|=1-2x,}    pois \mathsf{x&lt;0&lt;\frac{1}{2}.}


Por fim, temos que

\mathsf{\big|x-|x-1|\big|=1-2x\qquad para~x&lt;0.}


Bons estudos! :-)


dkiwilson: Obrigado
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