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

Toán Lớp 7: Tìm n thuộc N để: P = $\frac{6n+5}{3n+2}$ đạt GTLN

Toán Lớp 7: Tìm n thuộc N để:
P = $\frac{6n+5}{3n+2}$ đạt GTLN

Comments ( 1 )

  1. P=(6n+5)/(3n+2) (n\ne-2/3)
    P=(6n+4+1)/(3n+2)
    P=(6n+4)/(3n+2)+1/(3n+2)
    P=(2(3n+2))/(3n+2)+1/(3n+2)
    P=2+1/(3n+2)
    Để P đạt GTLN
    <=>1/(3n+2) đạt GTLN
    <=>3n+2 đạt GTN N
    <=>3n+2>=2
    Dấu $”$=$”$ xảy ra <=>n=0(t//m)
    =>P<=2+1/2=5/2
    Vậy max P=5/2 khi n=0

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