Tìm x biết a, 17 – { – x – [ – x – ( – x )]} = -16 b, 25 – { – x + [ x + ( – x )]} = 0 c, x – { [ – x + ( x + 3 ) ] – [( x + 3)- ( x – 2) ]} = 0 d,

0 bình luận về “Tìm x biết a, 17 – { – x – [ – x – ( – x )]} = -16 b, 25 – { – x + [ x + ( – x )]} = 0 c, x – { [ – x + ( x + 3 ) ] – [( x + 3)- ( x – 2) ]} = 0 d,”

1. Tìm x

    a ) 

        $ 17 – ( – x ) = -16$

        $ -x = 17 – ( -16 ) = 33$

   $⇒ – 33$

   $b ) 25 -$ { $- x + [ x + ( – x )]$} $= 0$

         $ 25 – ( -x ) = 0$

         $ – x = 25$

   $⇒ x =-25$

   $c ) x -$ { $[ – x + ( x + 3 ) ] – [( x + 3)- ( x – 2) ]$} $= 0$

          $x – 3 – 5 = 0$

          $x – 8 = 0$

   $⇒ x = 8$

   $d ) x +$ {$( x – 3 ) – (- x – 2 )]$} $= x$

          $x + ( 2x -1 ) = x$

          $2x – 1 = 0$

         $ 2x = 1$

   $⇒ x =$ $\dfrac{1}{2}$ 

   Tính nhanh : 

   $( -98 ) . ( 1 – 246 ) – 246 . 98$

   $= 98 . ( 246 – 1 ) – 246 . 98$

   $= 98 . 245 – 246 . 98$

   $= 98 . ( 245 – 246 ) $

   $= 98 . ( -1 ) $

   $= -98$

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