Substitute $\displaystyle s = x - 5$ in the formula for the surface area of a cube:

$\displaystyle A = 6s^{2}$

$\displaystyle A = 6 \left ( x - 5\right )^{2}$

$\displaystyle A = 6 \left ( x^{2} - 2 \cdot 5 \cdot x + 5^{2}\right )$

$\displaystyle A = 6 \left ( x^{2} - 10x +25\right )$

$\displaystyle A = 6 x^{2} - 60x +150$

To find the surface area of a cube, use the formula $\displaystyle 6s^{2}$, where $\displaystyle s$ represents the length of the side.  Since the side of the cube measures $\displaystyle 4$, we can substitute $\displaystyle 4$ in for $\displaystyle s$.

$\displaystyle 6(4)^{2}=96\: cm^{2}$

Your friend gives you a puzzle cube for your birthday. If the length of one edge is 5 cm, what is the surface area of the cube?

To find the surface area of a cube, use the following formula:

$\displaystyle SA_{cube}=6*s^2$

This works, because we have 6 sides, each of which has an area of $\displaystyle s^2$

Plug in our known to get our answer:

$\displaystyle SA_{cube}=6*(5cm)^2=6*25cm^2=150cm^2$

A cube has a side length of $\displaystyle 9 mm$, what is the surface area of the cube?

Surface area of a cube can be found as follows:

$\displaystyle SA_{cube}=6s^2$

Plug in our side length to find our answer:

$\displaystyle SA_{cube}=6(9mm)^2=6*81mm^2=486mm^2$

Making our answer:

$\displaystyle 486mm^2$

One of your holiday gifts is wrapped in a cube-shaped box. 

If one of the edges has a length of 6 inches, what is the surface area of the box?

We can find the surface area of a square by squaring the length of the side and then multiplying it by 6.

$\displaystyle SA_{square}=6s^2=6(6in)^2=216in^2$

To find the surface area of a cube, we will use the following formula:

$\displaystyle SA = 6a^2$

where a is the length of any side of the cube.

Now, we know the width of the cube is 6cm.  Because it is a cube, all sides are 6cm.  That is why we can choose any side to substitute into the formula.

Now, knowing this, we can substitute into the formula.  We get

$\displaystyle SA = 6 \cdot (6\text{cm})^2$

$\displaystyle SA = 6 \cdot 36\text{cm}^2$

$\displaystyle SA = 216\text{cm}^2$

To find the surface area of a cube, we will use the following formula:

$\displaystyle SA = 6a^2$

where a is the length of any side of the cube.  Note that all sides are equal on a cube.  That is why we can use any length in the formula. 

Now, we know the length of the cube is 7in.  

Knowing this, we can substitute into the formula.  We get

$\displaystyle SA = 6 \cdot (7\text{in})^2$

$\displaystyle SA = 6 \cdot 49\text{in}^2$

$\displaystyle SA = 294\text{in}^2$

To find the surface area of a cube, we will use the following formula.

$\displaystyle SA = 6a^2$

where a is the length of any side of the cube.

Now, we know the width of the cube is 4in.  Because it is a cube, all sides are equal (this is why we can use any length in the formula).  So, we will use 4in in the formula.  We get

$\displaystyle SA = 6 \cdot (4\text{in})^2$

$\displaystyle SA = 6 \cdot 16\text{in}^2$

$\displaystyle SA = 96\text{in}^2$

To find the surface area of a cube, we will use the following formula:

$\displaystyle SA = 6 \cdot l \cdot w$

where l is the length, and w is the width of the cube.

Now, we know the length of the cube is 12in.  Because it is a cube, all lengths, widths, and heights are the same.  Therefore, the width is also 12in.

Knowing this, we can substitute into the formula.  We get

$\displaystyle SA = 6 \cdot 12\text{in} \cdot 12\text{in}$

$\displaystyle SA = 6 \cdot 144\text{in}^2$

$\displaystyle SA = 864\text{in}^2$

While exploring an ancient ruin, you discover a small puzzle cube. You measure the side length to be $\displaystyle 12 cm$. Find the cube's surface area.

To find the surface area, use the following formula:

$\displaystyle SA=6s^2=6(12cm)^2=864cm^2$