Question

Consider the functiony = 3x^5 - 25x^3 + 60x+ 1. Use the first derivative test to decide whether this function has a maximum at x = 1. Which of the following describes what you found?

A. The derivative is positive to the left of x = 1 and positive to the right of x = 1, so the function has neither a relative maximum nor a minimum at x = 1.

B. None of these apply

C. The derivative is negative to the left of x = 1 and positive to the right of x = 1, so the function has a relative minimum at x = 1.

D. The derivative is positive to the left of x = 1 and negative to the right of x = 1, so the function has a relative maximum at x = 1.

E. The derivative is positive to the left of x = 1 and negative to the right of x = 1, so the function has a relative minimum at x = 1.

Answer 1

Answer:

Option A

Step-by-step explanation:

Expression for the given function is,

y = 3x⁵ - 25x³ + 60x + 1

First derivative of the given function will be,

y' = 15x⁴ - 75x² + 60

For the critical points of the function,

y' = 0

15x⁴ - 75x²+ 60 = 0

x = 1

On the left side of x = 1,

Let x = 0

y' = 15(0)⁴ - 75(0)²+ 60

y = 60 [Positive]

On the right side of x = 1,

Let x = 3

y' = 15x⁴ - 75x²+ 60

y' = 15(3)⁴ - 75(3)² + 60

y' = 1215 - 675 + 60

y' = 600 [Positive]

Since, the derivative is positive on both the sides of x = 1,

Function will have neither maximum neither minimum at x = 1.

Option A is the answer.