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222-9+11+12:2*14+14 = ? ( )

Toán Lớp 6: A,X×(-6)=(-14)+44 B,257-(X²-1)=177

Toán Lớp 6: A,X×(-6)=(-14)+44
B,257-(X²-1)=177

Comments ( 2 )

  1. #andy
    \[\begin{array}{l}
    x \times ( – 6) = ( – 14) + 44\\
    x \times ( – 6) = 30\\
    x =  – 5\\
     \Rightarrow x =  – 5\\
    {\rm{b)}}257 – \left( {{x^2} – 1} \right) = 177\\
     \Leftrightarrow {x^2} – 1 = 80\\
     \Leftrightarrow {x^2} = 81\\
     \Leftrightarrow \left[ \begin{array}{l}
    x = 9\\
    x =  – 9
    \end{array} \right.\\
     \Rightarrow S \in \{ 9; – 9\} 
    \end{array}\]

  2. a) $X x ( -6 ) = ( -14 ) + 44 $
    $Xx(-6)=30$
    $X=30:(-6)$
    $X=-5$
    $\text{Vậy x = -5}$
    $\text{b) 257 – ( x² – 1 ) = 177}$
    $\text{x² – 1 = 257 – 177}$
    $\text{x² – 1 = 80}$
    $\text{x² = 80 + 1}$
    $\text{x² = 81}$
    $\text{⇔ $\left[\begin{matrix} x² = 9²\\ x²=(-9)²\end{matrix}\right.$}$
    $\text{Vậy x = 9 hoặc x = -9}$

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222-9+11+12:2*14+14 = ? ( )