196k views
0 votes
The graph of f '(x) is continuous and decreasing with an x-intercept at x = 2. Which of the following statements must be true? (5 points)

The graph of f is always concave down.
The graph of f is always increasing.
The graph of f has an inflection point at x = 2.
The graph of f has a relative minimum at x = 2.

User Lebelinoz
by
8.7k points

1 Answer

2 votes

Answer:

The graph of f is always concave down ⇒ the first answer

Explanation:

* Lets explain how to solve the problem

- Remember that : If f(x) is a function then the solutions to the

equation f′(x) = 0 gives the maximum and minimum values to f(x)

- The value of x gives maximum if f′′(x) is negative and minimum if

f′′(x) is positive.

- Inflection points of the function f(x) are found the solutions of the

equation f′′(x) = 0

* Lets solve the problem

- The graph of f'(x) is continuous means that the graph is unbroken line

- The graph of f'(x) decreasing with an x-intercept at x = 2 means

f'(2) = 0

- The differentiation of a function equal to zero at the critical point

(minimum or maximum) of the function

∵ f'(x) = 0 at x = 2

∴ The x-coordinate of the critical point of f(x) is 2

- If the differentiation of the function is decreasing, then the critical

point of the function is maximum point

∵ f'(x) is decreasing

∴ The critical point of the f(x) is maximum point

- That means the slope of curve is negative

∴ The graph of f is concave down at x = 2

* The right answer is the graph of f is always concave down

User ThanhLePhan
by
7.5k points