Question

biết x,y là các số khác 0 và \(15^x:5^y=45^y\) tìm x,y

Answer 1

15^x : 5^y = 45^y

=> 15^x = 45^y * 5^y = (45 *5)^y = 225^y 

=> 15^x = 225^y 

=> 15^x  - 225^y = 0

=> x = 0, y = 0  

Answer 2

\(15^x:5^y=45^y\)

\(\Rightarrow\)\(15^x=45^y.5^y\)

\(\Rightarrow\)\(15^x=\left(45.5\right)^y\)

\(\Rightarrow\)\(15^x=225^y\)

\(\Rightarrow\)\(15^x=\left(15^2\right)^y\)

\(\Rightarrow\)\(15^x=15^{2y}\)

\(\Rightarrow\)\(x=2y\)

\(\Rightarrow\)\(\frac{x}{y}=2\)