## bless Group Title Which is equal to 3[f(2x)] for f(x) = 3x^2+3/2? a.15/2 b. 81/2 c. 9x^2+9/2 d.18x^2+9 one year ago one year ago

1. e.mccormick Group Title

What part of this is giving you trouble?

2. bless Group Title

when i try to substitute the f(x) to the 3[f(2x)] i can't get the answer

3. e.mccormick Group Title

You substitute 2x into f(x), then multiply through the whole thing by 3.

4. e.mccormick Group Title

Hmmm... and yes, if that is written right, I can see why that would not get an answer.

5. e.mccormick Group Title

Is it supposed to be $$3[f(2)]$$?? Rather than 2x?

6. bless Group Title

the answer is 108x^2 + 9/2?

7. bless Group Title

its 2x

8. e.mccormick Group Title

Yes, as written, $$108x^2 + \cfrac{9}{2}$$ would be correct.

if u want this answer then u should in question (3x)^2 instead of 3(x^2)

10. bless Group Title

well there was another option to solve this problem : if the correct answer is not in the given choices, write you answer

11. e.mccormick Group Title

Ah, yes... I see what Muhammad_Nauman_Umair is pointing out.

12. bless Group Title

13. e.mccormick Group Title

$$(2x)^2=4x^2$$ $$3\times 4x^2=12x^2$$ $$3\times 12x^2=36x^2$$ Which is what I got the first time... and when you said 108 I thought I had forgotten to multiply by 3.

14. e.mccormick Group Title

$$36x^2 + \cfrac{9}{2}$$ is what it should be.