# Which options gives f(7-x)

• Dec 27th 2009, 06:54 AM
pozat
Which options gives f(7-x)
I simply worked f(7-x) out and got the answer exactly described in (d). And x 19/3 and 0 ≤ x ≤ 7 seem appropriate too.

Now I wonder if there is any tricky thing in other areas. Would any fellow please take a look when you have time.

http://img97.imageshack.us/img97/6024/tma02q6.gif
• Dec 27th 2009, 06:58 AM
dedust
Quote:

Originally Posted by pozat
I simply worked f(7-x) out and got the answer exactly described in (d). And x 19/3 and 0 ≤ x ≤ 7 seem appropriate too.

Now I wonder if there is any tricky thing in other areas. Would any fellow please take a look when you have time.

http://img97.imageshack.us/img97/6024/tma02q6.gif

(d) is the answer
• Dec 27th 2009, 12:49 PM
HallsofIvy
Since $f(x)= \frac{-2x^2+1}{3x-2)^2}$, $f(7- x)= \frac{-2(7-x)^2+ 1}{3(7-x)-2)^2}= \frac{-2(49- 14x+ x^2)+ 1}{21- 3x- 2)^2}$ $= \frac{-97+ 28x- 2x^2}{(19- 3x)^2}$. That's "d".
• Dec 27th 2009, 03:33 PM
pozat
Thank you for all who give me reply and make MHF such a helpful site.

(Clapping)