Application of Derivatives 4 Question 19

20. The total number of local maxima and local minima of the function f(x)=(2+x)3,3<x1 x23,1<x<2 is

(2008, 3M)

(a) 0

(b) 1

(c) 2

(d) 3

Show Answer

Answer:

Correct Answer: 20. (d)

Solution:

  1. Given, f(x)=(2+x)3, if 3<x1 x2/3 if 1<x<2

f(x)=3(x+2)2, if 3<x1 23x13, if 1<x<2

Clearly, f(x) changes its sign at x=1 from +ve to ve and so f(x) has local maxima at x=1.

Also, f(0) does not exist but f(0)<0 and f(0+)<0. It can only be inferred that f(x) has a possibility of a minima at x=0. Hence, the given function has one local maxima at x=1 and one local minima at x=0.



जेईई के लिए मॉक टेस्ट

एनसीईआरटी अध्याय वीडियो समाधान

दोहरा फलक