Question

Is 392 a perfect cube? If not, find the smallest natural number by which

Answer 1

Answer:

No

7

Step-by-step explanation:

We can start by factoring 392 to see whether it is a cube. 392 is obviously divisible by 2 because the last digit is even, and dividing by two we get:

392 = 2 x 196

Again, 196 is divisible by 2, so we get:

392 = 2 x 2 x 98

And 98 is also divisible by 2:

392 = 2 x 2 x 2 x 49

49 is 7 times 7, so we can finish the prime factorization of 392:

392 = 2 x 2 x 2 x 7 x 7

This is the same as:

392 = 2^3 x 7^2

We can see 392 is not a cube because both numbers are not raised to a power divisible by 3.

In order to turn it into a cube, we'd need to make both prime factors raised to the power of a multiple of 3. 2 is already raised to one, but 7 is raised to the power of 2. In order to make that two divisible by 3, we can multiply by 7 so that our number is 2^3 x 7^3(2744), and this would be a cube(It's 14 cubed).