Question

Answer 1

\(\dfrac{x+11}{14-x}=\dfrac{2}{3}\Rightarrow\dfrac{x+11}{2}=\dfrac{14-x}{3}=\dfrac{x+11+14-x}{2+3}=\dfrac{25}{5}=5\)

\(\Rightarrow x+11=2.5=10\)

\(\Rightarrow x=10=11=-1\)

Answer 2

\(\dfrac{x+11}{14-x}=\dfrac{2}{3}\left(dk:x\ne14\right)\)

\(\Rightarrow3\left(x+11\right)=2\left(14-x\right)\)

\(\Rightarrow3x+33=28-2x\)

\(\Rightarrow3x+2x=28-33\)

\(\Rightarrow5x=-5\)

\(\Rightarrow x=-5:5\)

\(\Rightarrow x=-1\left(tm\right)\)

Vậy chọn đáp án B. \(x=-1\)