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

Toán Lớp 8: Giải bất phương trình a. /2x+3/ <7 b. /2x-3/ >5

Toán Lớp 8: Giải bất phương trình a. /2x+3/ <7 b. /2x-3/ >5

Comments ( 2 )

  1. Giải đáp:
    a)|2x+3|<7
    <=> \(\begin{cases}-7<2x+3\\2x+3<7\\\end{cases}\)
    <=> \(\begin{cases}-10<2x\\2x<4\\\end{cases}\)
    <=> \(\begin{cases}-5<x\\x<2\\\end{cases}\)
    <=>-5<x<2
    b)|2x-3|>5
    <=> \(\left[ \begin{array}{l}2x-3>5\\2x-3<-5\end{array} \right.\) 
    <=> \(\left[ \begin{array}{l}2x>8\\2x<-2\end{array} \right.\) 
    <=> \(\left[ \begin{array}{l}x>4\\x<-1\end{array} \right.\) 

  2. a.|2x+3|<7
    $⇔$\(\left[ \begin{array}{l}2x+3 <7\\-(2x+3)<7\end{array} \right.\)
    $⇔$\(\left[ \begin{array}{l}2x +3<7\\-2x-3<7\end{array} \right.\)
    $⇔$\(\left[ \begin{array}{l}2x<4\\-2x<10\end{array} \right.\)
    $⇔$\(\left[ \begin{array}{l}x<2\\x>5\end{array} \right.\)
    b.|2x -3| > 5
    $⇔$\(\left[ \begin{array}{l}2x -3 >5\\-(2x -3) >5 \end{array} \right.\)
    $⇔$\(\left[ \begin{array}{l}2x -3 >5\\-2x +3 > 5\end{array} \right.\)
    $⇔$\(\left[ \begin{array}{l}2x>8\\-2x>2\end{array} \right.\)
    $⇔$\(\left[ \begin{array}{l}x>4\\x<-1\end{array} \right.\)
    #hoctot

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

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