2x= 3y => [tex]\frac{x}{3}= \frac{y}{2} => \frac{1}{5}.\frac{x}{3} = \frac{1}{5}.\frac{y}{2}=> \frac{x}{15}=\frac{y}{10}[/tex]
4y=5z => [tex]\frac{y}{5}=\frac{z}{4} => \frac{1}{2}.\frac{y}{5}= \frac{1}{2}.\frac{z}{4} => \frac{y}{10} = \frac{z}{8}[/tex]
Nên [tex]\frac{x}{15}=\frac{y}{10}= \frac{z}{8} => \frac{2x}{30}=\frac{3y}{30}=\frac{5z}{40}[/tex]
Áp tc dãy tỉ số bằng nhau ta có:
[tex] \frac{2x}{30}=\frac{3y}{30}=\frac{5z}{40}= \frac{2x-3y+5z}{30-30+40} = \frac{3}{10}[/tex]
Hay [tex]\frac{x}{15}=\frac{y}{10}= \frac{z}{8} = \frac{3}{10} [/tex]
Do đó x = [tex]\frac{3}{10}.15 =\frac{9}{2}[/tex]
y = [tex]\frac{3}{10}.10 = 3[/tex]
z = [tex]\frac{3}{10}.8 =\frac{12}{5}[/tex]