Question

Tìm x,y,z biết x/y=3/5, 7y=6z và 4x+8y-9z=-3

ccs bnj giải hẳn ra giùm mìn coi 3 like nhé

Answer 1

\(\frac{x}{y}=\frac{3}{5}\Leftrightarrow5x=3y\Leftrightarrow35x=21y\)

\(7y=6z\Leftrightarrow21y=18z\)

Suy ra \(35x=18z\)

\(4x+8y-9z=-3\)

\(40x+80y-90z=-30\)

\(5x+35x+80y-90z=-30\)

\(83y-72z=-30\)

\(83y-84y=-30\left(Vì6z=7y\Leftrightarrow-72z=-84y\right)\)

\(y=30\)

\(x=18\)

\(z=35\)