Tìm x 1)x.(x+70)=0 2)(x+12).(x-3)=0 3)(-x+5).(3-x)=0 4)x.(2+x).(7-x)=0 5)(x-1).(x+2).(-x-3)=0

0 bình luận về “Tìm x 1)x.(x+70)=0 2)(x+12).(x-3)=0 3)(-x+5).(3-x)=0 4)x.(2+x).(7-x)=0 5)(x-1).(x+2).(-x-3)=0”

1. a, x.(x+70) = 0

   TH1 x = 0

   TH2 x+70 = 0

          x        = -70

   Vậy x ∈ { 0 ; -70 }

   b, (x+12).(x-3) = 0

   TH1 x+12 = 0

          x        = -12

   TH2 x – 3 = 0

          x       = 3

   Vậy x ∈ {-12 ; 3 }

   c, (-x+5).(3-x) = 0

   TH1 -x+5 = 0

            x     = 5

   TH2 3 – x = 0

                x = 3

   Vậy x ∈ {5 ; 3 }

   d, x.(2+x).(7-x) = 0

   TH1 x = 0

   TH2  2+x = 0

                x = -2

   TH3 7-x = 0

              x = 7

   Vậy x ∈ {-2 ; 0 ; 7 }

   e, (x-1).(x+2).(-x-3)=0

   TH1 x-1 = 0

          x     = 1

   TH2 x+2 = 0

          x      = -2

   TH3 -x-3 = 0

           x     = -3

   Vậy x ∈ {1 ; -2 ; -3 } 

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2. $1)x(x+70)=0$

   `=>`\(\left[ \begin{array}{l}x=0\\x+70=0\end{array} \right.\) `=>`\(\left[ \begin{array}{l}x=0\\x=-70\end{array} \right.\)

   Vậy `x in {0;-70}`

   $2)(x+12)(x-3)=0$

   `=>`\(\left[ \begin{array}{l}x+12=0\\x-3=0\end{array} \right.\) `=>`\(\left[ \begin{array}{l}x=-12\\x=3\end{array} \right.\)

   Vậy `x in {-12;3}`

   $3)(-x+5)(3-x)=0$

   `=>`\(\left[ \begin{array}{l}-x+5=0\\3-x=0\end{array} \right.\) `=>`\(\left[ \begin{array}{l}x=5\\x=3\end{array} \right.\)

   Vậy `x in {5;3}`

   $4)x(2+x)(7-x)=0$

   `=>`\(\left[ \begin{array}{l}x=0\\2+x=0\\7-x=0\end{array} \right.\) `=>`\(\left[ \begin{array}{l}x=0\\x=-2\\x=7\end{array} \right.\)

   Vậy `x in {0;-2;7}`

   $5)(x-1)(x+2)(-x-3)=0$

   `=>`\(\left[ \begin{array}{l}x-1=0\\x+2=0\\-x-3=0\end{array} \right.\) `=>`\(\left[ \begin{array}{l}x=1\\x=-2\\x=-3\end{array} \right.\)

   Vậy `x in {1;-2;-3}`.

    

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