Question

Tìm cặp số (x;y) biết:

\(\frac{1+5y}{24}=\frac{1+7y}{7x}=\frac{1+9y}{2x}\)

Answer 1

\(\frac{1+7y}{7x}=\frac{1+9y}{2x}\) \(\Leftrightarrow\frac{1+7y}{7}=\frac{1+9y}{2}\)

\(\Leftrightarrow\left(1+7y\right)2=7\left(1+9y\right)\)

\(\Leftrightarrow2+14y=7+63y\)

\(\Leftrightarrow63y-14y=2-7\)

\(\Leftrightarrow y=-\frac{5}{49}\)

Thay \(x=-\frac{5}{49}\) vào biểu thức ta có :

\(\frac{1+7.\frac{-5}{49}}{7.x}=\frac{1+9.\frac{-5}{49}}{2x}\)

\(\Leftrightarrow x=2\)

Vậy..