Q23 / 54 · JEE Advanced 2019 (Paper 2) · Mathematics
Let
Let be all the points of local maximum of and be all the points of local minimum of
Then which of the following options is/are correct?
Let be all the points of local maximum of and be all the points of local minimum of
Then which of the following options is/are correct?
- Correct answerAfor every
- B
- Correct answerCfor every
- Correct answerDfor every
Solution
…(i)
for maxima/minima
maxima/minima will occur
Where

Case
For example
In at point
and at
at
hence from equation (i)
in goes from positive to negative
hence is maxima
Similarly … are point of maxima and all lies in
Case
In
for example at
at
and at
hence from equation (i)
in goes from negative to positive
so, for the minima
and for the maxima
Hence …
now,
Similarly,
…(b)
Therefore …(c)
Now consider
From (b) and (c)
for maxima/minima
maxima/minima will occur
Where

Case
For example
In at point
and at
at
hence from equation (i)
in goes from positive to negative
hence is maxima
Similarly … are point of maxima and all lies in
Case
In
for example at
at
and at
hence from equation (i)
in goes from negative to positive
so, for the minima
and for the maxima
Hence …
now,
Similarly,
…(b)
Therefore …(c)
Now consider
From (b) and (c)
Hence, the correct answer is options: 'A', 'C', 'D'.