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

Toán Lớp 10: Giải hệ phương trình $\begin{cases} xy(y+1)+y^2+1=4y\\xy^2(x+2)+\frac{1}{y^2}+y^2=5 \end{cases}$

Toán Lớp 10: Giải hệ phương trình $\begin{cases} xy(y+1)+y^2+1=4y\\xy^2(x+2)+\frac{1}{y^2}+y^2=5 \end{cases}$

Comments ( 1 )

  1. Bạn kham khảo
    {(xy(y+1)+y^2+1=4y),(xy^2(x+2)+1/y^2+y^2=5):}
    <=>{(x(x+1)+y+1/y=4),(y^2(x^2+2x+1)+1/y^2=5):}
    <=>{(y(x+1)+1/y+x=4),(y^2(x+1)^2+1/y^2=5):}
    Đặt u=y(x+1)+1/y;v=x+1
    =>{(u+v=5),(u^2-2v=5):}
    <=>{(v=5-u),(u^2+2u-15=0):}
    <=>{(x=-5),(v=10):}∨{(u=3),(v=2):}
    Hay {(y=(x+1)+1/y=-5),(x+1=10):}∨{(y(x+1)+1/y=3),(x+1=2):}
    <=>{(10y^2+5y+1=0),(x=9):}∨{(2y^2-3y+1=0),(x=1):}
    <=>{(x=1∧y=1),(x=1∧y=1/2):}
    S={(1;1),(1;1/2)}

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

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