\(=\lim\limits_{x\rightarrow0}\dfrac{\left(x^2+\pi^{21}\right)\left(1-2x\right)^{\dfrac{1}{7}}-\pi^{21}}{x}\)
\(=\lim\limits_{x\rightarrow0}\dfrac{\dfrac{1}{7}\left(1-2x\right)^{-\dfrac{6}{7}}.\left(-2\right)\left(x^2+\pi^{21}\right)+2x\left(1-2x\right)^{\dfrac{1}{7}}}{1}\)
\(=\dfrac{1}{7}.\left(-2\right).\pi^{21}=...\)