Ta có:
\(\begin{array}{l}f'\left( x \right) = 2x \Rightarrow f'\left( 1 \right) = 2\\\varphi '\left( x \right) = 4 + \dfrac{\pi }{2}\cos \dfrac{{\pi x}}{2} \Rightarrow \varphi '\left( 1 \right) = 4\\ \Rightarrow \dfrac{{f'\left( 1 \right)}}{{\varphi '\left( 1 \right)}} = \dfrac{2}{4} = \dfrac{1}{2}\end{array}\)
