Question

\(\dfrac{x}{x+3}-1\) 

Rút gọn

Answer 1

\(\dfrac{x-\left(x+3\right)}{x+3}=\dfrac{x-x-3}{x+3}=\dfrac{-3}{x+3}\)

Answer 2

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Answer 3

\(\dfrac{x}{x+3}-1=0\)

\(\Leftrightarrow\dfrac{x\left(x-3\right)}{\left(x+3\right)\left(x-3\right)}-\dfrac{\left(x+3\right)\left(x-3\right)}{\left(x+3\right)\left(x-3\right)}=0\)

\(\Leftrightarrow x^2-3x-\left(x^2-3x+3x-9\right)=0\)

\(\Leftrightarrow x^2-3x-x^2+9=0\)

\(\Leftrightarrow-3x+9=0\)

\(\Leftrightarrow-3x=-9\)

\(\Leftrightarrow x=3\)