ای کیٹ · ریاضی · 6 سوالات
نام: ____________________ تاریخ: ____________
What is the value of the derivative of x⁴ - 3x² + 2 at x = 1?
At which values of x does f(x) = x³ - 3x have stationary points?
The function f(x) = x³ - 3x has a local maximum at:
A particle moves so that its position is s = t³ - 6t². What is its velocity at t = 2?
What is d/dx of x e^x?
How fast is the area of a circle changing with respect to its radius when the radius is 3?
1. A, 2. A, 3. B, 4. A, 5. C, 6. D
The derivative is 4x³ - 6x. At x = 1 it equals 4 - 6 = -2.
f'(x) = 3x² - 3 = 0 gives x² = 1, so x = 1 or x = -1.
f''(x) = 6x. At x = -1 the second derivative is negative, so this is a local maximum.
v = ds/dt = 3t² - 12t. At t = 2, v = 12 - 24 = -12.
By the product rule, the derivative is e^x + x e^x = e^x (1 + x).
A = pi r², so dA/dr = 2 pi r = 6 pi at r = 3.