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

Toán Lớp 8: (2/căn x + căn x/căn x+2):2 căn x/x+2 căn x

Tháng Mười Hai 6, 2022 Toán học 2 Comments 0 views

Toán Lớp 8: (2/căn x + căn x/căn x+2):2 căn x/x+2 căn x

Comments ( 2 )

  1. aivilanlan
    aivilanlan
    6 Tháng Mười Hai, 2022 at 12:54 chiều
    Reply
    ***Lời giải***
    P=(\frac{2}{\sqrt{x}}+\frac{\sqrt{x}}{\sqrt{x}+2}):\frac{2\sqrt{x}}{x+2\sqrt{x}}  
    =\frac{2(\sqrt{x}+2)+x}{\sqrt{x}(\sqrt{x}+2)}:\frac{2\sqrt{x}}{x+2\sqrt{x}} 
    =\frac{x+2\sqrt{x}+4}{\sqrt{x}(\sqrt{x}+2)}.\frac{\sqrt{x}(\sqrt{x}+2) }{2\sqrt{x}} 
    =\frac{x+2\sqrt{x}+4}{2\sqrt{x}}
    ĐKXĐ: x>0 
    Ta có: P=3
    =>\frac{x+2\sqrt{x}+4}{2\sqrt{x}}=3
    <=>\frac{x+2\sqrt{x}+4}{2\sqrt{x}}-3=0
    <=>\frac{x+2\sqrt{x}+4-3.2\sqrt{x}}{2\sqrt{x}}=0
    <=>\frac{x+2\sqrt{x}+4-6\sqrt{x}}{2\sqrt{x}}=0
    <=>\frac{x-4\sqrt{x}+4}{2\sqrt{x}}=0
    <=>\frac{(\sqrt{x}-2)^2}{2\sqrt{x}}=0
    =>(\sqrt{x}-2)^2=0
    <=>\sqrt{x}-2=0
    <=>\sqrt{x}=2
    <=>x=4(N)
    Vậy x=4 thì P=3

  2. hienchaudiem
    hienchaudiem
    6 Tháng Mười Hai, 2022 at 12:53 chiều
    Reply
    ~ Tham khảo :
    (2/sqrtx+sqrtx/(sqrtx+2)) \div (2sqrtx)/(x+2sqrtx)
    = (2(sqrtx+2)+x)/(sqrtx(sqrtx+2)) * (x+2sqrtx)/(2sqrtx)
    = (2sqrtx+4+x)/(sqrtx(sqrtx+2)) * (sqrtx(sqrtx+2))/(2sqrtx)
    = (2sqrtx+4+x) * 1/(2sqrtx)
    = (2sqrtx+4+x)/(2sqrtx)

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

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