Is A=s^2 is a area formula that show a joint variation

Question

Is A=s^2, A=π^2, A=l•w formula that show joint variation?

Answer 1

Hi Dedreke,

 

joint variation occurs when a variable like A in this case, depends or varies directly as the product of 2 or more other variables.

 

An example of 'varies directly' is this.

 

If y = 4x, then y varies directly to x because as x increases, y increases by the same factor

 

Now take your choices:

 

A=s² is not an example of joint variation. A does increase as s increases but not by the same factor and there is only the one variable (s) that determines A

 

A=π² is not an example of joint variation. A does not vary directly with any variable. It remains constant.

 

The last choice, A=l·w is an example of joint variation. A varies directly with l and w. As l increases, so does A. As w increases, so does A.