Question

Can someone please clarify this? I don't understand the steps to get the answer.
If f (x) = 3x^2-4
Write f (2x) in its simplest form

Answer 1

http://www.purplemath.com/modules/fcnops.htm
:) try that

Answer 2

Hello, Katski,

You're given a function: f (x) = 3x^2 - 4, and you're asked to evaluate this function when the input is 2x instead of just x.

You might want to re-write the given function as f( ) = 3( )^2 - 4

and then write "2x" inside the parentheses. Simplify the result, and you've then got your answer.

Answer 3

thanks, D-L. My only suggestion is that you evaluate the function with 2x as input, not just 2 as input.

Answer 4

Hmm I see, so f (x) = 3 (2x)^2 - 4 ?
Then i just work it out as normal?
@mathmale

Answer 5

*f (2x) = ********

Answer 6

f (2x) = 3 (2x)^2 - 4. Yes. You must do exponentiation BEFORE multiplication, so focus on (2x)^2. That equals what?

Answer 7

mmm, 4x^2

Answer 8

Great. Now re-write f (2x) = 3 (2x)^2 - 4 using your latest result.

Answer 9

f (2x) = 3(4x^2) - 4 i think

Answer 10

@mathmale

Answer 11

Yes, that is correct, but simplify/expand it all the way.

Answer 12

Drew:

Just expand your f (2x) = 3(4x^2) - 4: f(2x) = 12x^2-4. that's it.