Applications Of Derivatives Question 247
Question: Function $ f(x)=2x^{3}-9x^{2}+12x+29 $ is monotonically decreasing, when
[RPET 1996]
Options:
A) $ x<2 $
B) x > 2
C) x >1
D) 1< x < 2
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Answer:
Correct Answer: D
Solution:
Function is monotonically decreasing, when $ {f}’(x)<0 $
therefore $ 6x^{2}-18x+12<0 $
therefore $ x^{2}-3x+2<0 $
therefore $ x^{2}-2x-x+2<0 $
therefore $ (x-2)(x-1)<0 $ ,
$ \therefore x\in 1<x<2 $ .
BETA
