Question

[linh angela nguyễn]

Biết . Khi đó

Answer 1

[Phạm Nguyễn Tất Đạt]

\(\frac{1+y}{9}=\frac{1+2y}{7}\Rightarrow7\left(1+y\right)=9\left(1+2y\right)\Rightarrow7+7y=9+18y\Rightarrow7y-18y=9-7\)

\(\Rightarrow-11y=2\Rightarrow y=\frac{-2}{11}\)

\(\Rightarrow\frac{1+-\frac{2}{11}}{9}=\frac{1+3\cdot\left(-\frac{2}{11}\right)}{x}\)

\(\Rightarrow\frac{\frac{9}{11}}{9}=\frac{\frac{5}{11}}{x}\)

\(\Rightarrow\frac{1}{11}=\frac{\frac{5}{11}}{x}\Rightarrow x=11\cdot\frac{5}{11}=5\)

Vậy x=5

Answer 2

[Ngô Đức Chung]

5