\(\left(\dfrac{7}{2}-x\right)^2-\dfrac{4}{5}=-\dfrac{4}{25}\\ \Rightarrow\left(\dfrac{7}{2}-x\right)^2=\dfrac{16}{25}\\ \Rightarrow\left[{}\begin{matrix}\dfrac{7}{2}-x=\dfrac{4}{5}\\\dfrac{7}{2}-x=-\dfrac{4}{5}\end{matrix}\right.\\ \Rightarrow\left[{}\begin{matrix}x=\dfrac{27}{10}\\x=\dfrac{43}{10}\end{matrix}\right.\)