Question

Using the completing-the-square method, rewrite f(x) = x2 + 4x − 1 in vertex form.

f(x) = (x + 2)2 + 1
f(x) = (x + 2)2
f(x) = (x + 2)2 + 4
f(x) = (x + 2)2 − 5

Answer 1

welcome to open study

Answer 2

tanks

Answer 3

yeah

Answer 4

can you help me with this problem

Answer 5

what does it mean by "rewrite f(x) = x2 + 4x − 1 in vertex form."

Answer 6

@Mehek14

Answer 7

@marigirl @moazzam07

Answer 8

factorizing,
so basically when you expand it out again, you should have your original equation.

Answer 9

but how do i turn fx to vetex form

Answer 10

vertex

Answer 11

o i didnt see where you said factor sorry

Answer 12

vertex form also means turning point on graph. i.e at which point on the x axis will the parabola have its minimum point.
Best way to go about is start factorizing the equation given to you f(x) = x^2 + 4x − 1

May start factorising first part - x^2+4x .. what will that get us to

Answer 13

x(x+4) ???

Answer 14

let try it another way .. i am going to factorise it to
\[f(x)= (x+2)^{2}\]
This will ensure I have it in vertex form... now i need to manipulate it a little so that my final equation will look like \[f(x)=x ^{2}+4x-1\]
so now, what constant value will i need to add to the top equation to make it same as the second equation ..

Answer 15

i dont know 2?

Answer 16

see what u get when you expand f(x)=(x+2^2:

we get x^2+4x+4 ..... but i need x^2+4x-1 .. so what number do i need to add/minus so i wil get to x^2+4x-

Answer 17

1

Answer 18

i need to minus 5

Answer 19

where u get that from lol im so confused

Answer 20

(x+2)^2-5

Answer 21

sorry i dont think i helped...

Answer 22

oooo ok i understand wher i am i was confused with the vertex form i mixed it with a different formula

Answer 23

no actually you did i just thought to hard

Answer 24

ok, well you can always expand the answers given to you and see which is the original equation

Answer 25

ok thanksss