JEE Main 2022 · 30 Jun · Shift 1 · Mathematics Q9

MathematicsSingle correct+4 / -1Question 9 of 90

Let $f(x)=4x^3-11x^2+8x-5$ , $x\in\mathbf R$ . Then $f$ :

has a local minima at

x=\dfrac12

has a local minima at

x=\dfrac34

is increasing in

\left(\dfrac12,\dfrac34\right)

is decreasing in

\left(\dfrac12,\dfrac43\right)

Answer and worked solution

Official answer: D

Derivative. $f'=12x^2-22x+8=2(2x-1)(3x-4)$ , negative between $\frac12$ and $\frac43$ .

(D)

Topics:Monotonicity

JEE Main 2022 · 30 Jun · Shift 1, Mathematics question 9