[tex]\dfrac{5}{4}+4\left(\dfrac{3}{4}-\dfrac{1}{2}\right)^2=\dfrac{5}{4}+4\left(\dfrac{3}{4}-\dfrac{2}{4}\right)^2\\\\=\dfrac{5}{4}+4\left(\dfrac{1}{4}\right)^2=\dfrac{5}{4}+4\cdot\dfrac{1}{16}\\\\=\dfrac{5}{4}+\dfrac{4}{16}=\dfrac{5}{4}+\dfrac{1}{4}\\\\=\dfrac{6}{4}=\dfrac{3}{2}[/tex]
