Applications Of Derivatives Question 222
Question: The least value of k for which the function $ x^{2}+kx+1 $ is an increasing function in the interval $ 1<x<2 $ is
Options:
A) - 4
B) - 3
C) - 1
D) - 2
Show Answer
Answer:
Correct Answer: D
Solution:
To be increasing, $ \frac{d}{dx}(x^{2}+kx+1)>0 $
$ \Rightarrow 2x+k>0 $
For $ x\in (1,,2) $ , the least value of $ k $ is -2.
BETA
