Differentiation Question 333
Question: $ f(x)=x^{2}-3x $ , then the points at which $ f(x)=f’(x) $ are
Options:
A) 1, 3
B) 1, - 3
C) - 1, 3
D) None of these
Show Answer
Answer:
Correct Answer: D
Solution:
$ f(x)=x^{2}-3x $ and $ f’(x)=2x-3 $
But $ f(x)=f’(x)\Rightarrow x^{2}-3x=2x-3 $
Therefore $ x^{2}-5x+3=0 $
$ \therefore x=\frac{5\pm \sqrt{25-12}}{2}=\frac{5\pm \sqrt{13}}{2} $ .
BETA
