For the curve $y=5 x-2 x^3$, if $x$ increases at the rate of 2 units/sec, the rate of change in the slope of…
For the curve $y=5 x-2 x^3$, if $x$ increases at the rate of 2 units/sec, the rate of change in the slope of the curve at $x=3$ is ......../sec
- $72$
- $27$
- $-72$
- $-27$
Solution
$y=5 x-2 x^3$
$\frac{d y}{d x}=5-6 x^2$
$\therefore$ Slope of curve is $5-6 x^2$.
$\therefore \quad m=5-6 x^2 \Rightarrow \frac{d m}{d t}=(-12 x) \frac{d x}{d t}$
$\left(\frac{d m}{d t}\right)_{x=3}=-12(3) \times 2=-72$ $\left[\because \frac{d x}{d t}=2\right]$
$\Rightarrow$ Rate of change of slope at $x=3$ is -72
Asked in: AP EAMCET 2021 (24 Aug Shift 2)
Practice more Applications of Derivatives questions on Aicharya