Question

Calcule as coordenadas do vértice da parábolas que representam as seguintes funções :
c) y= x2 - 4x

Answer 1

$y=x^2-4x\\\\ a=1\ ;\ b=-4\ ;\ c=0\\\\\\ x_v= \frac{-b}{2a} \to x_v=\frac{-(-4)}{2*1} \to x_v=\frac{4}{2} \to x_v=2\\\\\\ \Delta=b^2-4ac\to \Delta=(-4)^2-4*1*0\to \Delta=16-0\to \Delta=16 \\\\ y_v=\frac{-\Delta}{4a} \to y_v=\frac{-16}{4*1} \to y_v=\frac{-16}{4} \to y_v=-4\\\\\\\\ V=\{2 ; -4\}$