Do 2 đồ thị cùng tiếp xúc với \(y=2x+1\) tại \(M\left(1;3\right)\Rightarrow\left\{{}\begin{matrix}f'\left(1\right)=g'\left(1\right)=2\\f\left(1\right)=g\left(1\right)=3\end{matrix}\right.\)
Ta có:
\(h'\left(x\right)=f'\left(x\right).g\left(x\right)+f\left(x\right).g'\left(x\right)+2021\)
\(\Rightarrow\left\{{}\begin{matrix}h'\left(1\right)=f'\left(1\right).g\left(1\right)+f\left(1\right).g'\left(1\right)+2021=2.3+3.2+2021=2033\\h\left(1\right)=g\left(1\right).g\left(1\right)+2021.1=3.3+2021=2030\end{matrix}\right.\)
Phương trình tiếp tuyến:
\(y=2033\left(x-1\right)+2030\Leftrightarrow y=2033x-3\)