# Determining the range for a function to be increasing

#### swag312

##### New member
Hi, it would be really nice if someone could give me a correct answer with a little explanation to this question. Thanks.

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#### Opalg

##### MHB Oldtimer
Staff member
Re: Math help

Hi, it would be really nice if someone could give me a correct answer with a little explanation to this question. Thanks.
Hi swag312 , and welcome to MHB.

One of the things that the derivative tells you is whether the function is increasing or decreasing. The function increases when the derivative is positive, and decreases when the derivative is negative.

As $x$ goes from $-4$ to $+4$, you can see from the graph that the function starts by decreasing, then it increases, and finally it decreases again. So what is the interval along the $x$-axis during which the function is increasing?

#### swag312

##### New member
Re: Math help

Hi swag312 , and welcome to MHB.

One of the things that the derivative tells you is whether the function is increasing or decreasing. The function increases when the derivative is positive, and decreases when the derivative is negative.

As $x$ goes from $-4$ to $+4$, you can see from the graph that the function starts by decreasing, then it increases, and finally it decreases again. So what is the interval along the $x$-axis during which the function is increasing?
Ahh, so it looks like it's increasing from -2 to 2 in which case the answer is A ? (-2;2) ?

#### Opalg

##### MHB Oldtimer
Staff member
Re: Math help

Ahh, so it looks like it's increasing from -2 to 2 in which case the answer is A ? (-2;2) ?
Yes.