
Sums of cubes can be factored as

So

Hey there! The answer to your question is simple. First off, it does not ask for oxygen atoms, so that is just there to mess with you. It says carbon, to hydrogen. That means put the number of carbon, 2, before the number of hydrogen, 4. So, The answer is A - 2:4.
Hi there!
For any 45 45 90 right triangle, the length of the hypotenuse is always the square root of 2 times one of the legs.
To get the lengths of the leg, let's divide the length of the hypotenuse by the square root of 2.
We get the following:

When simplifying fractions like this, we want to avoid having radicals on the bottom. In order to remove the radical from the denominator, let's multiply the numerator and the denominator by the square root of 2.
We get the following:

That's your answer.
Have an awesome day! :)
- collinjun0827, Junior Moderator
A number is a perfect square (or a square number) if its square root is an integer; that is to say, it is the product of an integer with itself. Here, the square root of 20 is about 4.472. Thus, the square root of 20 is not an integer, and therefore 20 is not a square number.