Question

Please HELP:
Using the completing-the-square method, rewrite f(x) = x^2 + 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

do you know what a "perfect square trinomial" is?
sometimes just called a "perfect square"

Answer 2

yes

Answer 3

\[x^2+bx+c=(x+\frac{b}{2})^2+c-\frac{b^2}{4}\]

Answer 4

would it be D then?

Answer 5

\[f(x) = x^2+4x-1\]\[=(x^2+4x)-1\]\[=(x^2+4x+\color{red}{4})-1\color{red}{-4}\]\[=\boxed{(x-2)^2-5}\]

Answer 6

so... \(\bf f(x)=x^2+4x-1\implies f(x)=(x^2+4x+{\color{red}{ \square ?}}^2)-1\)


what do you think is the missing number?

Answer 7

Lovely.

Answer 8

correct @iwanttogotostanford

Answer 9

one more?

Answer 10

@jdoe0001 why isn't `\boxed` working for me?

Answer 11

Which of the following values "completes the square," or creates a perfect square trinomial, for x2 + 6x + ___?

1
3
6
9

Answer 12

i believe its 9 but i just want to make sure

Answer 13

\[c=\left(\frac{6}{2}\right)^2 = ~?\]

Answer 14

9!

Answer 15

\[\color{red}{\checkmark}\]

Answer 16

i really need help with this one real quick, thanks for all your help..:-)

Answer 17

Solve x2 + 8x − 3 = 0 using the completing-the-square method.

x = four plus or minus the square root of three
x = negative four plus or minus the square root of three
x = four plus or minus the square root of nineteen
x = negative four plus or minus the square root of nineteen

Answer 18

use the method we used above.

Answer 19

so , B?

Answer 20

I don't know,I didn't solve it.

Answer 21

could you help me? :_)

Answer 22

first add +3 to both sides.

Answer 23

what do you get, @iwanttogotostanford ?

Answer 24

the same but on the left -6 and on the right 3

Answer 25

??....

Answer 26

okay, if you add +3 to both sides , the answer i was looking for is, x\(^2\)+8x=3

Answer 27

@Jhannybean sorry, i was gone