- #1

- 14

- 0

## Homework Statement

http://postimg.org/image/48919pl1x/

## Homework Equations

f(f(x))= (x^4)-4(x^2)+2,

## The Attempt at a Solution

[f(x)]^2=

(x^4)-4(x^2)+2=

[(x-2)^2]-(4x^2)+2

i can't seem to square root (x^4)-4(x^2)+2...

You are using an out of date browser. It may not display this or other websites correctly.

You should upgrade or use an alternative browser.

You should upgrade or use an alternative browser.

- Thread starter GreenTea09
- Start date

- #1

- 14

- 0

http://postimg.org/image/48919pl1x/

f(f(x))= (x^4)-4(x^2)+2,

[f(x)]^2=

(x^4)-4(x^2)+2=

[(x-2)^2]-(4x^2)+2

i can't seem to square root (x^4)-4(x^2)+2...

Precalculus Mathematics Homework Help News on Phys.org

- #2

- 4,244

- 93

## Homework Statement

http://postimg.org/image/48919pl1x/

## Homework Equations

f(f(x))= (x^4)-4(x^2)+2,

## The Attempt at a Solution

[f(x)]^2=

(x^4)-4(x^2)+2=

[(x-2)^2]-(4x^2)+2

i can't seem to square root (x^4)-4(x^2)+2...

The question states that f(x) is a polynomial. Use this.

http://en.wikipedia.org/wiki/Polynomial

- #3

- 14

- 0

let f(x)=a(x^2)+bx+c

(a(x^2)+bx+c)*(a(x^2)+bx+c) =(x^4)-4(x^2)+2

comparing the coefficient of x^2

2c+b^2=-4 ---eqn(2)

comparing the coefficient of constant,

i get a c value of sqrt2 and -sqrt2

which i try to fit into eqn(2) but dosent work out..

- #4

Science Advisor

Homework Helper

Gold Member

Dearly Missed

- 10,106

- 136

f(f(x)) must also be evaluated on the bf(x)+c terms!

- #5

Mentor

- 37,235

- 9,400

The image link is broken.## Homework Statement

http://postimg.org/image/48919pl1x/

No one else pointed this out, so I will. f(f(x)) is not the same as [f(x)]## Homework Equations

f(f(x))= (x^4)-4(x^2)+2,

## The Attempt at a Solution

[f(x)]^2=

That's not relevant here, since you are not being asked to solve for f(x) in the equation [f(x)](x^4)-4(x^2)+2=

[(x-2)^2]-(4x^2)+2

i can't seem to square root (x^4)-4(x^2)+2...

What you're working with is a composite of f with itself -- (f o f)(x) --, not the square of f(x).

Share:

- Replies
- 19

- Views
- 827

- Replies
- 7

- Views
- 577

- Replies
- 4

- Views
- 578

- Replies
- 12

- Views
- 601

- Replies
- 8

- Views
- 419

- Replies
- 4

- Views
- 485

- Replies
- 19

- Views
- 452

- Replies
- 16

- Views
- 933

- Replies
- 1

- Views
- 119

- Replies
- 10

- Views
- 823