\(\left(-\dfrac{1}{2}\right)^2-\dfrac{1}{2}\left[\dfrac{3}{4}-\dfrac{1}{4}\cdot\left(5^3:5^2\right)\right]+\dfrac{3}{4}\)
\(=\dfrac{1}{4}+\dfrac{3}{4}-\dfrac{1}{2}\left[\dfrac{3}{4}-\dfrac{1}{4}\cdot5\right]\)
\(=1-\dfrac{1}{2}\cdot\left(\dfrac{3}{4}-\dfrac{5}{4}\right)\)
\(=1+\dfrac{1}{4}=\dfrac{5}{4}\)