# Thread: The function f (x)

1. ## The function f (x)

Let $\displaystyle f(x) = 1 - 2x^{2}$ and determine

b) $\displaystyle f(1-\sqrt{3})$

I know that I´m supposed to put the above functions number 1 - squart 3 on the functions x place.

This is how far I´ve come:
I´m getting the number to
$\displaystyle f(1-\sqrt{3})$=$\displaystyle 1 - 2 (1-\sqrt{3})^{2}$

is this correct and if, what should I do now?

2. ## Re: The function f (x)

Looks good so far. Expand and simplify.

3. ## Re: The function f (x)

Originally Posted by Quacky
Looks good so far. Expand and simplify.
$\displaystyle \gg 1 - 2 (1-\sqrt{3}) (1-\sqrt{3})$

Is this correct? Should I now eliminate $\displaystyle \sqrt{3}$ now?

4. ## Re: The function f (x)

Originally Posted by Bluerabbits
$\displaystyle \gg 1 - 2 (1-\sqrt{3}) (1-\sqrt{3})$

Is this correct? Should I now eliminate $\displaystyle \sqrt{3}$ now?
You've not expanded, you've written the equation in the OP just in a different way.

To expand $\displaystyle (1-\sqrt3)^2$ use FOIL (or whichever method you learned for expanding $\displaystyle (a+b)^2$)