Applications Of Derivatives Question 90
Question: Let $ f,( 1 )=-,2 $ and $ f’(x)\ge 4.2 $ for $ 1\le x\le 6 $ . The smallest possible value of f(6) is
Options:
A) 9
B) 12
C) 15
D) 19
Show Answer
Answer:
Correct Answer: D
Solution:
[d] Using Lagrange’s mean value theorem, for some $ c\in (1,6) $
$ f’(c)=\frac{f(6)-f(1)}{5}=\frac{f(6)+2}{5}\ge 4.2 $ Or $ f(6)+2\ge 21 $ Or $ f(6)\ge 19 $
BETA
