How do you find the vertex of a parabola $y=(-x-1)(x+7)$ ?

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Answer 1 · 2018-04-02T10:59:01

Vertex is at $(-4,9)$

$y=(-x-1)(x+7) or y= -(x+1)(x+7)$ or

$y= -(x^2+8x+7) or y= -(x^2+8x)-7$ or

$y= -(x^2+8x+16)+16-7$ or

$y= -(x+4)^2+9$ . Comparing with vertex form of

equation $y = a(x-h)^2+k ; (h,k)$ being vertex we find

here $h=-4 , k=9 :.$ Vertex is at $(-4,9)$

graph{(-x-1)(x+7) [-25.32, 25.3, -12.66, 12.66]} [Ans]

How do you find the vertex of a parabola y=(-x-1)(x+7)y=(-x-1)(x+7)?