Write the quadratic function in vertex form.
-$$y = x ^ { 2 } - 20 x + 91$$
A) $y = ( x + 10 ) ^ { 2 } + 9$
B) $y = ( x + 10 ) ^ { 2 } - 9$
C) $y = ( x - 10 ) ^ { 2 } + 9$
D) $y = ( x - 10 ) ^ { 2 } - 9$

Question

Quizplus · Accepted Answer

The vertex form of a quadratic function is $y = a(x - h)^2 + k$, where $(h, k)$ is the vertex of the parabola. To convert $y = x^2 - 20x + 91$ into vertex form, complete the square: $y = (x^2 - 20x + 100) - 100 + 91 = (x - 10)^2 - 9$.

Write the Quadratic Function in Vertex Form y=x2−20x+91y = x ^ { 2 } - 20 x + 91y=x2−20x+91

Write the Quadratic Function in Vertex Form $y = x ^ { 2 } - 20 x + 91$