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

Toán Lớp 8: giúp vs mn Cho `(x-x^2)/(5-5x^2)=1/(x.C)` Tìm biểu thức C

Toán Lớp 8: giúp vs mn
Cho
(x-x^2)/(5-5x^2)=1/(x.C)
Tìm biểu thức C

Comments ( 2 )

  1. Giải đáp:
    \frac{x-x^2}{5-5x^2}=\frac{1}{x.C} (x\ne +-1)
    <=> \frac{x(1-x)}{5(1-x^2)}=\frac{1}{Cx}
    <=> \frac{x(1-x)}{5(1-x)(1+x)}=\frac{1}{Cx}
    <=> \frac{x}{5(1+x)}=\frac{1}{Cx}
    <=> Cx^2=5(1+x)
    <=> Cx^2=5+5x
    <=> C=\frac{5+5x}{x^2}
    Vậy C=frac{5+5x}{x^2}

  2. \frac{x-x^2}{5-5x^2}=\frac{1}{x}.C (ĐK: x \ne -1; x \ne 1)
    =>\frac{x.(1-x)}{5.(1-x^2)}=\frac{1}{x}.C
    =>\frac{x.(1-x)}{5.(1-x).(1+x)}=\frac{1}{x}.C
    =>\frac{x}{5.(1+x)}=\frac{1}{x}.C
    =>\frac{x}{5+5x}=\frac{1}{x}.C
    =>C=\frac{x}{5+5x}:\frac{1}{x}
    =>C=\frac{x}{5+5x}.\frac{x}{1}
    =>C=\frac{x^2}{5+5x}
    Vậy C=\frac{x^2}{5+5x}

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