Question

X/2=y/3,y/5=z/7va2x+3y+z=172

Answer 1

\(\frac{x}{2}=\frac{y}{3};\frac{y}{5}=\frac{z}{7}\Leftrightarrow\frac{x}{10}=\frac{y}{15}=\frac{z}{21}\)

theo tính chất dãy tỉ số bằng nhau ta có :

\(\frac{x}{10}=\frac{y}{15}=\frac{z}{21}=\frac{x+y+z}{10+15+21}=\frac{172}{36}=\frac{43}{9}\)

x/10=43/9 => x=430/9

y/15=43/9 => y=215/3

z/21=43/9 => z=301/3

Answer 2

hello

Answer 3

\(\frac{x}{2}=\frac{y}{3}\Rightarrow\frac{x}{10}=\frac{y}{15}\)

\(\frac{y}{5}=\frac{z}{7}\Rightarrow\frac{y}{15}=\frac{z}{21}\)

\(\Rightarrow\frac{x}{10}=\frac{y}{15}=\frac{z}{21}\)

\(\Rightarrow\frac{2x}{20}=\frac{3y}{45}=\frac{z}{21}=\frac{2x+3y+z}{20+45+21}=\frac{172}{86}=2\)

=> x=20,y=30,z=42

Answer 4

làm lại :

x/2=y/3;y/5=z/7 <=> x/10=y/15=z/21

theo tính chất dãy tỉ số bằng nhau ta có :

\(\frac{x}{10}=\frac{y}{15}=\frac{z}{21}=\frac{2x}{2.10}=\frac{3y}{3.15}=\frac{z}{21}=\frac{2x+3y+z}{20+45+21}=\frac{172}{86}=2\)

x/10=2 => x=2.10=20

y/15=2 => y=2.15=30

z/21=2 => z=2.21=42