Algebra help me ;(?

Question

Is the total surface area A of a cube a function of the edge c of the cube? If it is not a function, explain why not. If it is a function, write the function rule and then evaluate the function for a cube with edge 2.5 cm.

How do I do this question? Please show me how you would work it out and tell me how to reckognize a function? This one in particular.

Answer 1

since it is a cube all edges are of equal length. Each of the 6 sides has area =c^2
The total surface area is a funtion A=6c^2

A(2.5cm)=6*2.5^2
=37.5 cm^2

Answer 2

First off, the surface are of a cube is basically the area of all the sides combined. Since there are six sides (all of equal area)
Surface Area = 6 * side^2

A function is something that has exactly one output for every input. So, basically each x value can evaluate to only 1 y value.

If you had a set of points:
{(1,5) , (2,7) , (3,10) , (1,17)}
This isn't a function, because the x value of 1 could equal either 5 or 17.

The Surface Area thing is function becuase there is only 1 y value for every x value

You have f(x) = 6 * x^2
It is basically the Surface area formula, using functions.


f(2.5) = 6 *2.5^2 = 37.5