Question

Cho hàm số y=f(x) thỏa mãn f(x+y)=f(x).f(y) . Biết f(2019)=2020. tính f(2020)

Answer 1

Ta có:\(f\left(x\right).f\left(y\right)=f\left(x.y\right)\)

\(\Rightarrow f\left(x+y\right)=f\left(x.y\right)\)

\(\Rightarrow f\left(2019\right)=f\left(0+2019\right)=f\left(0.2019\right)=f\left(0\right)=2020\)

\(\Rightarrow f\left(2020\right)=f\left(0+2020\right)=f\left(0.2020\right)=f\left(0\right)\)

\(\Rightarrow f\left(2019\right)=f\left(2020\right)=f\left(0\right)=2020\)

Answer 2

khó quá.

Answer 3

Tại sao : \(f\left(0+2019\right)=f\left(0.2019\right)\)? logic, hay do mk ngu ... 2019 = 0 à ?