Question

What are the coordinates of the vertex of the graph of the function y = -3x^2 - 12x + 3?

a. (-2,29)
b. (2, 15)
c. (2, -9)
d. (2, -15)

Answer 1

For the x-coordinate I got, x = 2. But for some reason I got -57 as my y-coordinate?

Answer 2

ok so were is the graph

Answer 3

There is no graph. You have to find the coordinates.

Answer 4

ok cool

Answer 5

@cwrw238 What did I do wrong?

Answer 6

try negative 2

Answer 7

i'm just checking it out

Answer 8

yes its -2

Answer 9

how?

Answer 10

convert it to vertex form and you'll see - the y coordinate is 15

Answer 11

at vertex slope of graph is 0
put dy/dx=0 you will get x

Answer 12

yes - you can do it by differentiation

Answer 13

and after that put value of x in y = -3x^2 - 12x + 3 you will get corresponding y
i get pair (-2,15)

Answer 14

maybe clover has 'nt done calculus yet
have you familiar with differentiation clover?

Answer 15

nope lol im in algebra I and just learning quadratic functions

Answer 16

I got my x-coordinate by using the equation of the line of symmetry which is
x = -b/2a

Answer 17

if I use 2 as my x-coordinate I get -57 as my y-coordinate. if I use -2 as my x-coordinate I get -33?

Answer 18

Ok we have

-3x^2 - 12x + 3
= -3(x^2 + 4x + 1)


= -3[(x +2)^2 -4 + 1)

this gives the x coordinate of the vertex = -2
now plug -2 into the original equation and we get y = 5

vertex is at (-2,15)

Answer 19

oooohhh okay! Thanks for the help! ((:

Answer 20

thats ok - its not one of the options but it is correct

Answer 21

-b/2a gives you -2

- (-12) / -6 = 12/-6 = -2