The vertex of this parabola is at (-2, 5). Which of the following could be its equation?

A. y = 3(x - 2)2 - 5
B. y = 3(x - 2)2 + 5
C. y = 3(x + 2)2 + 5
D. y = 3(x + 2)2 - 5

Question

The vertex of this parabola is at (-2, 5). Which of the following could be its equation? 



 		A.	y = 3(x - 2)2 - 5
 		B.	y = 3(x - 2)2 + 5
 		C.	y = 3(x + 2)2 + 5
 		D.	y = 3(x + 2)2 - 5

anonymous · Answer

What i do is go to https://www.desmos.com/calculator and put in each of the equations. I know theres a trick to finding the answer without graphing, but i cant remember it

anonymous · Answer

I don't understand website you give me but thank you anyways.

whpalmer4 · Answer

Vertex formula for a parabola is:
$$y = (x-h)^2 + k$$
where the vertex is at $(h,k)$

whpalmer4 · Answer

You know the vertex, so plug that into the formula and compare notes.

Sorry, that should be $$y = a(x-h)^2 + k$$where $a$ is a constant that will equal $3$ in this case.

whpalmer4 · Answer

There are an infinite number of parabolas with the same vertex, so the value of $a$ selects which one you get.