JEE PYQ: Application Of Derivatives Question 56
Question 56 - 2019 (08 Apr Shift 1)
If $S_1$ and $S_2$ are respectively the sets of local minimum and local maximum points of the function, $f(x) = 9x^4 + 12x^3 - 36x^2 + 25$, $x \in \mathbb{R}$, then:
(1) $S_1 = {-2}$; $S_2 = {0, 1}$
(2) $S_1 = {-2, 0}$; $S_2 = {1}$
(3) $S_1 = {-2, 1}$; $S_2 = {0}$
(4) $S_1 = {-1}$; $S_2 = {0, 2}$
Show Answer
Answer: (3)
Solution
$f’(x) = 36x(x-1)(x+2) = 0$. Sign analysis shows $x = -2$ (min), $x = 0$ (max), $x = 1$ (min). $S_1 = {-2, 1}$, $S_2 = {0}$.
BETA
