Question

Cho hàm số y= ax-2. Tìm a, biết f(5)=8

Answer 1

Ta có \(\left\{{}\begin{matrix}f\left(x\right)=ax-2\\f\left(5\right)=8\end{matrix}\right.\) \(\Rightarrow5a-2=8\) \(\Rightarrow a=2\)

Answer 2

Ta có {f(x)=ax−2f(5)=8{f(x)=ax−2f(5)=8  

Answer 3

Ta có: f(5)=8

nên 5x-2=8

hay x=2