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

Toán Lớp 9: 2m+3n=1 thì m bằng bao nhiêu? m+n=-5 thì n bằng bao nhiêu?

Toán Lớp 9: 2m+3n=1 thì m bằng bao nhiêu?
m+n=-5 thì n bằng bao nhiêu?

Comments ( 1 )

  1.       $\left \{ {{2m+3n=1} \atop {m+n=-5}} \right.$
    $⇔\left \{ {{2m+3n=1} \atop {2m+2n=-10}} \right.$
    $⇒2m+3n-(2m+2n)=1-(-10)→n=11$
    $→m=-5-n=-5-11=-16$
    $⇒\left \{ {{m=-16} \atop {n=11}} \right.$ 

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

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