\(\Rightarrow\dfrac{3x}{60}=\dfrac{4y}{60}=\dfrac{5z}{60}\Rightarrow\dfrac{x}{20}=\dfrac{y}{15}=\dfrac{z}{12}=\dfrac{x-\left(y+z\right)}{20-\left(15+12\right)}=\dfrac{-21}{-7}=3\\ \Rightarrow\left\{{}\begin{matrix}x=60\\y=45\\z=36\end{matrix}\right.\)
3x=4y⇒x4=y3(1)3x=4y⇒x4=y3(1)
4y=5z⇒y5=z4(2)4y=5z⇒y5=z4(2)
Từ (1) và (2) => x20=y15=z12x20=y15=z12.
Theo t/c dãy tỉ số = nhau:
x20=y15=z12=x−(y+z)20−(15+12)=−21−7=3x20=y15=z12=x−(y+z)20-(15+12)=-21-7=3
⇒x20=3⇒x=3.20=60⇒x20=3⇒x=3.20=60
⇒y15=3⇒y=3.15=45⇒y15=3⇒y=3.15=45
⇒z12=3⇒z=3.12=36⇒z12=3⇒z=3.12=36
Vậy x=60; y=45; z=36.
