Functions Question 380
Question: If $ f(x)=4x-x^{2},x\in R, $ then $ f(a+1)-f(a-1) $ is equal to
Options:
A) $ 2(4-a) $
B) $ 4(2-a) $
C) $ 4(2+a) $
D) $ 2(4+a) $
Show Answer
Answer:
Correct Answer: B
Solution:
[b] $ f(x)=4x-x^{2} $
$ \Rightarrow f(a+1)-f(a-1)={4(a+1)-{{(a+1)}^{2}}} $ $ -{4(a-1)-{{(a-1)}^{2}}} $ $ =8-{{{(a+1)}^{2}}-{{(a-1)}^{2}}}=8-4a=4(2-a) $
BETA
