Question

Tìm các số x, y, z, biết:        \(\frac{x+16}{9}=\frac{y-25}{16}=\frac{z+9}{25}\)và \(2x^3-1=15\)

 

Answer 1

\(2x^3-1=15\)

\(2x^3=16\)

\(x^3=8\Rightarrow x=2\)

\(\Rightarrow\frac{x+16}{9}=\frac{y+25}{16}=\frac{z+9}{25}\)trở thành

\(\frac{2+16}{9}=\frac{y-25}{16}=\frac{z+9}{25}\)

\(\Rightarrow\frac{y-25}{16}=\frac{z+9}{25}=\frac{18}{9}=2\)

suy ra \(\frac{y-25}{16}=2\Rightarrow y-25=32\Rightarrow y=57\)

\(\frac{z+9}{25}=2\Rightarrow z+9=50\Rightarrow z=41\)

vậy \(x=2;y=57;z=41\)

Answer 2

\(2x^3-1=15\Leftrightarrow x^3=8\Leftrightarrow x=2\)

\(\Rightarrow\frac{2+16}{9}=\frac{y-25}{16}=\frac{z+9}{25}\)

\(\Rightarrow y=57;z=41\)