Question

Quais são as coordenadas do vértice de uma parábola definida pela função quadrática y = x2 – 8x 7?.

Answer 1

$\Large\boxed{\begin{array}{l}\sf y=x^2-8x+7\\\sf\Delta=b^2-4ac\\\sf\Delta=(-8)^2-4\cdot1\cdot7\\\sf\Delta=64-28\\\sf\Delta=36\\\sf x_V=-\dfrac{b}{2a}\\\\\sf x_V=-\dfrac{-8}{2\cdot1}\\\\\sf x_V=4\\\\\sf y_V=-\dfrac{\Delta}{4a}\\\\\sf y_V=-\dfrac{36}{4\cdot1}\\\\\sf y_V=-9\\\sf \blue{V(4,-9)}\end{array}}$