$ frac{2}{x-14}$ - $ frac{5}{x-13}$ =$ frac{2}{x-9}$ -$ frac{5}{x-11}$

Question

bichha · Answer

Đ&aacute;p &aacute;n:   2/(x-14)-5/(x-13)=2/(x-9)-5/(x-11)   => 2(x-13)(x-9)(x-11)-5(x-14)(x-9)(x-11)=2(x-14)(x-13)(x-11)   => (2x-26)(x-9)(x-11)-(5x-70)(x-9)(x-11)=(2x-28)(x-13)(x-11)   => (2x&sup2;-18x-26x+234)(x-11)-(5x&sup2;-45x-70x+630)(x-11)=(2x&sup2;-26x-28x+364)(x-11)   => (2x&sup2;-44x+234)(x-11)-(5x&sup2;-115x+630)(x-11)=(2x&sup2;-54x+364)(x-11)   => 2x&sup3;-22x&sup2;-44x&sup2;+484x+234x-2574-(5x&sup3;-55x&sup2;-115x&sup2;+1265x+630x-6930)=(2x&sup3;-22x&sup2;-54x&sup2;+594x+364x-4004)   => 2x&sup3;-22x&sup2;-44x&sup2;+484x+234x-2574-5x&sup3;+55x&sup2;+115x&sup2;-1265x-630x+6930-2x&sup3;+22x&sup2;+54x&sup2;-594x -364x+4004   => -5x&sup3;+158x&sup2;-2135x+8360=0   => x=6,2 v&agrave; x=12,7 v&agrave; x=12,7 (mode 5->4)   Vậy S={6,2;12,7}

bichlien · Answer

Đ&aacute;p &aacute;n:17       Giải th&iacute;ch c&aacute;c bước giải:    2/x-14-5/x-13=-3x-44/(x-14)(x-13)   2/x-9-5/x-11=3x-23/(x-11)(x-9)   -3x-44/(x-14)(x-13)=-3x-23/(x-11)(x-9)   2/x-14-5/x-13=2/x-9-5/x-11   -2/x-9+5/x-11-5/x-13+2/x-14=0   -10(x-17)/(x-14)(x-13)(x-11)(x-9)=0   1/x-14=0   1/x-13=0   1/x-11=0   1/x-9=o   => 17

$\frac{2}{x-14}$ – $\frac{5}{x-13}$ =$\frac{2}{x-9}$ -$\frac{5}{x-11}$

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