\(3x=2y=>\frac{x}{2}\)\(=\frac{y}{3}\)
Ta có:\(x=2k;y=3k\)
Thay x;y trông phép tính trên ta được
\(\left(2k+3k\right)^3\)\(-\left(x-y\right)^3\)\(=126\)
\(5k^3\)\(-\left(-1k\right)^3\)\(=126\)
\(5^3\)\(k^3\)\(+1k^3=126\)
\(125k^3\)\(+1k^3=126\)
\(k^3\)\(\left(125+1\right)\)\(=126\)
\(k^3\)\(126=126\)
\(k^3\)\(=126:126=1\)
\(=>k=1\)
\(x=2k=2.1=2\)
\(y=3k=3.1=3\)
\(=>x=2;y=3\)