Question

Giải giúp mình câu 7

Answer 1

7, ĐKXĐ:\(x\ne2\)

\(\dfrac{1}{x-2}+\dfrac{3-x}{2-x}=-3\\ \Leftrightarrow\dfrac{1}{x-2}+\dfrac{x-3}{x-2}=-3\\ \Leftrightarrow\dfrac{1+x-3}{x-2}=-3\\ \Rightarrow x-2=-3\left(x-2\right)\\ \Leftrightarrow x-2=6-3x\\ \Leftrightarrow x-2-6+3x=0\\ \Leftrightarrow4x-8=0\\ \Leftrightarrow x=2\left(ktm\right)\)

Answer 2

7: \(\Leftrightarrow\dfrac{1}{x-2}+\dfrac{x-3}{x-2}=\dfrac{-3\left(x-2\right)}{x-2}\)

\(\Leftrightarrow x-2=-3\left(x-2\right)\)

=>x-2=0

hay x=2(loại)

8: \(\Leftrightarrow\left(x+5\right)^2-\left(x-5\right)^2=20\)

\(\Leftrightarrow x^2+10x+25-x^2+10x-25=20\)

=>20x=20

hay x=1(nhận)