440,516 views
16 votes
16 votes
A cube has a volume of 8 ft³. What is its edge length?

User Robert Waddell
by
2.4k points

2 Answers

22 votes
22 votes
2ft. Area of cube is LxWxH and all sides are equal since cubes are made of squares!
User Kenneth Truong
by
3.0k points
18 votes
18 votes

Let's call x the edge length of that cube.

The volume V of a cube with edge length x is:

V = x³

We know that the volume of that cube is V = 8 ft³. So, in order to find the edge length x, we can replace V by 8 ft² in the above relation:

V = x³

8 ft³ = x³

Now we can rewrite 8 as 2³ since

2³ = 2 * 2 * 2 = 8

So, we find:

8 ft³ = x³

2³ ft³ = x³

Now, since 2³ and ft³ have both the same exponent, we can write:

2³ ft³ = (2 ft)³

So, we have:

(2 ft)³ = x³

And since we have the same odd exponent for both sides of the equation, the basis must be the same:

2 ft = x

x = 2 ft

Therefore, the edge length is 2 ft.

A cube has a volume of 8 ft³. What is its edge length?-example-1
User Zhong Huiwen
by
2.8k points