Question

Answer 1

a:

ĐKXĐ: \(x\notin\left\{-1;2\right\}\)

 \(\Leftrightarrow x-2-5x-5=-15\)

\(\Leftrightarrow4x=-8\)

hay x=-2(nhận)

b:

ĐKXĐ: \(x\notin\left\{2;-2\right\}\)

 \(\Leftrightarrow x^2-3x+2-x^2-2x=-5x+2\)

\(\Leftrightarrow0x=0\)

Vậy: S={x|\(x\notin\left\{2;-2\right\}\)}

Answer 2

a)     \(\dfrac{1}{x+1}\)-\(\dfrac{5}{x-2}\)=\(\dfrac{15}{\left(x+1\right)\left(2-x\right)}\)

<=>(x-2)-5(x+1)=15

<=>(x-2)-(5x+5)=15

<=>-x+2-5x-5=15

<=>-x-5x=15-2+5

<=>-6x=18

<=>x=-3

 

Answer 3

b)    \(\dfrac{x-1}{x+2}\)-\(\dfrac{x}{x-2}\)=\(\dfrac{5x-2}{4-x^2}\)

<=>\(\dfrac{x-1}{x+2}\)-\(\dfrac{x}{x-2}\)=\(\dfrac{5x-2}{\text{(x+2)(x-2)}}\)

<=>x-1(x+2)-x(x+2)=5x-2

<=>x+2x-x-2-x-2=5x-2

<=>2x-x=5x-2

<=>2x-x-5x=-2

<=>-4x=-2

<=>x=2