Functions Question 436

Question: Let $ f(x)=\frac{\alpha x^{2}}{x+1},x\ne -1. $ The value of $ \alpha $ for which $ f(a)=a,(a\ne 0) $ is

Options:

A) $ 1-\frac{1}{a} $

B) $ \frac{1}{a} $

C) $ 1+\frac{1}{a} $

D) $ \frac{1}{a}-1 $

Show Answer

Answer:

Correct Answer: C

Solution:

[c] Given $ f(x)=\frac{\alpha x^{2}}{x+1},x\ne -1;f(a)=a $ $ \frac{\alpha a^{2}}{a+1}=a\Rightarrow \alpha =1+\frac{1}{a}. $