Let f(x) = x3e- 3x, x > 0. Then, the maximum value of f(x) is
e- 3
3e- 3
27e- 9
A.
e- 3
Given, f(x) = x3e- 3x
On differentiating w.r.t. x, we get
f'(x) = 3x2e- 3x + x3e- 3x(- 3)
= x23e- 3x(1 - x)
= 3e- 3x(x2 - x3)
For maxima and minima, put f' (x) = 0
Now, f''(x) = 3e- 3x(2x - 3x2) - 9e- 3x(x2 - x3)
= 3e- 3x(3x3 - 6x2 + 2x)
At x = 1, f''(1) = 3e- 3(- 1) < 0, maxima
Hence, it is maximum at x = 1.
If the normal to the curve y = f(x) at the point (3, 4) make an angle 3/4 with the positive x-axis, then f'(3) is
1
- 1
-
The equation of normal of x2 + y2 - 2x + 4y - 5 = 0 at (2, 1) is
y = 3x - 5
2y = 3x - 4
y = 3x + 4
y = x + 1