Question

Find the vertex of the following function: f (x) = 3x^2 + 6x - 5 .

Answer 1

the formula is: -b/2a ?

Answer 2

x of vertex = -b/2a
y of vertex, insert x of vertex into standard formula and solve for y

Answer 3

I got -b/2a = -(6/2(3) = -(6/6) = -1 ?

Answer 4

let me work it and check for you

Answer 5

mocham, you have the correct x coordinate of the vertex

Answer 6

yes, now what's the y?

Answer 7

the question doesn't specify if it wants the x or y vertex BUT I have two possible answers so it probably wants it - that makes sense

Answer 8

yes you need both since the vertex is in the form (x,y)

Answer 9

ie it's a point

Answer 10

normally it will be in the form of (x,y)
sometimes they will ask the height of the vertex which is y
sometimes they will ask the location of the vertex which will be x

Answer 11

depends on the wording of the question, beware of trickery

Answer 12

now its k=f(-b/2a) ?

Answer 13

f(-b/2a)
like f(-2) where yhey want you to evaluate function at x = -2
k=f(-b/2a) should mean that they want the y of the vertex.

Anyone concur with this statement?

Answer 14

the statement is asking you to evaluate the function at the x of the vertex

Answer 15

and return it's y value

Answer 16

k= -1(-b/2a) wouldn't my answer be 1?

Answer 17

mocham, you found above that -b/2a = -1

so f(-b/2a) = f(-1) = ???

Answer 18

-1?

Answer 19

f (x) = 3x^2 + 6x - 5

f(-1) = 3(-1)^2 + 6(-1) - 5

f(-1) = ???

Answer 20

k= f(-b/2a)
k= f(-1)
y = f(-1)
all of these are asking the same thing