## What does the 2nd derivative test tell you?

The second derivative may be used to determine local extrema of a function under certain conditions. If a function has a critical point for which f′(x) = 0 and the second derivative is positive at this point, then f has a local minimum here. This technique is called Second Derivative Test for Local Extrema.

**What is second derivative used for?**

The second derivative of a function f can be used to determine the concavity of the graph of f. A function whose second derivative is positive will be concave up (also referred to as convex), meaning that the tangent line will lie below the graph of the function.

**What is the difference between first and second derivative test?**

The biggest difference is that the first derivative test always determines whether a function has a local maximum, a local minimum, or neither; however, the second derivative test fails to yield a conclusion when y” is zero at a critical value.

### When can we not use the second derivative test?

If f′(c)=0 and f″(c)=0, or if f″(c) doesn’t exist, then the test is inconclusive.

**What happens if the second derivative is 0?**

Since the second derivative is zero, the function is neither concave up nor concave down at x = 0. It could be still be a local maximum or a local minimum and it even could be an inflection point.

**How do you know if the second derivative is positive or negative?**

The second derivative tells whether the curve is concave up or concave down at that point. If the second derivative is positive at a point, the graph is bending upwards at that point. Similarly if the second derivative is negative, the graph is concave down.

## What if the second derivative test is 0?

Since the second derivative is zero, the function is neither concave up nor concave down at x = 0. It could be still be a local maximum or a local minimum and it even could be an inflection point. Let’s test to see if it is an inflection point. We need to verify that the concavity is different on either side of x = 0.

**What do first and second derivative mean?**

While the first derivative can tell us if the function is increasing or decreasing, the second derivative. tells us if the first derivative is increasing or decreasing.

**Can the second derivative test fail?**

Note: Even though it is often easier to use than the first derivative test, the second derivative test can fail at some points, as noted above. If the second derivative test fails, then the first derivative test must be used to classify the point in question.

### What is the first and second derivative used for?

In other words, just as the first derivative measures the rate at which the original function changes, the second derivative measures the rate at which the first derivative changes. The second derivative will help us understand how the rate of change of the original function is itself changing.

**Why do we need the second derivative test?**

The second derivative test is useful when trying to find a relative maximum or minimum if a function has a first derivative that is zero at a certain point. Since the first derivative test fails at this point, the point is an inflection point.

**How does the second derivative test work?**

Second derivative test (single variable) After establishing the critical points of a function, the second derivative test uses the value of the second derivative at those points to determine whether such points are a local maximum or a local minimum.

## What is the purpose of the second derivative?

One purpose of the second derivative is to analyze concavity and points of inflection on a graph.

**What is a relative minimum in calculus?**

relative minimum. [′rel·ə·tiv ′min·ə·məm] (mathematics) A value of a function at a point x 0 which is equal to or less than the values of the function at all points in some neighborhood of x 0.