# High School Math : Finding Regions of Increasing and Decreasing Value

## Example Questions

### Example Question #1 : Applications Of Derivatives

Define .

Give the interval(s) on which  is decreasing.

Explanation:

is decreasing on those intervals at which .

We need to find the values of  for which . To that end, we first solve the equation:

These are the boundary points, so the intervals we need to check are:

,  and

We check each interval by substituting an arbitrary value from each for .

Choose

increases on this interval.

Choose

decreases on this interval.

Choose

increases on this interval.

The answer is that  decreases on .

### Example Question #1 : Finding Regions Of Increasing And Decreasing Value

Define .

Give the interval(s) on which  is increasing.

Explanation:

is increasing on those intervals at which .

We need to find the values of  for which . To that end, we first solve the equation:

These are the boundary points, so the intervals we need to check are:

,  and

We check each interval by substituting an arbitrary value from each for .

Choose

increases on this interval.

Choose

decreases on this interval.

Choose

increases on this interval.

The answer is that  increases on

### Example Question #1 : Finding Regions Of Increasing And Decreasing Value

At what point does  shift from increasing to decreasing?

It does not shift from increasing to decreasing

Explanation:

To find out where the graph shifts from increasing to decreasing, we need to look at the first derivative.

To find the first derivative, we can use the power rule. We lower the exponent on all the variables by one and multiply by the original variable.

We're going to treat  as  since anything to the zero power is one.

Notice that  since anything times zero is zero.

If we were to graph , would the y-value change from positive to negative? Yes. Plug in zero for y and solve for x.

### Example Question #15 : Calculus I — Derivatives

At what point does  shift from decreasing to increasing?

Explanation:

To find out where it shifts from decreasing to increasing, we need to look at the first derivative. The shift will happen where the first derivative goes from a negative value to a positive value.

To find the first derivative for this problem, we can use the power rule. The power rule states that we lower the exponent of each of the variables by one and multiply by that original exponent.

Remember that anything to the zero power is one.

Can this equation be negative? Yes. Does it shift from negative to positive? Yes. Therefore, it will shift from negative to positive at the point that .

### Example Question #2 : Derivatives

At what value of  does  shift from decreasing to increasing?

It does not shift from decreasing to increasing

Explanation:

To find out when the function shifts from decreasing to increasing, we look at the first derivative.

To find the first derivative, we can use the power rule. We lower the exponent on all the variables by one and multiply by the original variable.

Anything to the zero power is one.

From here, we want to know if there is a point at which graph changes from negative to positive. Plug in zero for y and solve for x.

This is the point where the graph shifts from decreasing to increasing.