Respuesta :

[tex]8x^{2}+4x\\\\=8\left(x^{2}+\frac{1}{2}x \right)\\\\=8\left(x+\frac{1}{4} \right)^{2}-8\left(\frac{1}{16} \right)\\\\\boxed{f(x)=8\left(x+\frac{1}{4} \right)^{2}-\frac{1}{2}}[/tex]