Question

1.
Write the equation of the parabola in vertex form.



A. y = –(x – 1)2 + 3

B. y = –x2 – 4

C. y = –x2 + 3

D. y = –x2 + 4

Answer 1

$~~~~~~\textit{vertical parabola vertex form} \\\\ y=a(x- h)^2+ k\qquad \begin{cases} \stackrel{vertex}{(h,k)}\\\\ \stackrel{"a"~is~negative}{o pens~\cap}\qquad \stackrel{"a"~is~positive}{o pens~\cup} \end{cases} \\\\[-0.35em] \rule{34em}{0.25pt}$

$\begin{cases} h= 0\\ k = 4 \end{cases}\implies y=a(x-0)^2+4~\hfill \textit{we also know that} \begin{cases} x = 1\\ y = 3 \end{cases} \\\\\\ 3=a(1-0)^2+4\implies 3=1a+4\implies \boxed{-1=a} \\\\\\ y=-1(x-0)^2+4\implies \blacktriangleright y = -x^2+4\blacktriangleleft$

Answer 2

Answer:

A.    y = –(x – 1)2 + 3    = Rewrite in vertex form and use this form to find the vertex  (h,k).    (1,3)=  Already in vertex form.  y=−(x−1)2+3

OR

D.    y = –x^2 + 4    = Rewrite in vertex form and use this form to find the vertex  (h,k).    (0,4)=  Find the vertex form.     y=−(x+0)2+4

Step-by-step explanation:

A.    y = –(x – 1)2 + 3    = Rewrite in vertex form and use this form to find the vertex  (h,k).    (1,3)=  Already in vertex form.  y=−(x−1)2+3

B.    y = –x^2 – 4    = Rewrite in vertex form and use this form to find the vertex  (h,k).    (0,−4)=   Find the vertex form.     y=−(x+0)2−4

C.    y = –x^2 + 3     = Rewrite in vertex form and use this form to find the vertex  (h,k).    (0,3)=  Find the vertex form.     y=−(x+0)2+3

D.    y = –x^2 + 4    = Rewrite in vertex form and use this form to find the vertex  (h,k).    (0,4)=  Find the vertex form.     y=−(x+0)2+4