Answer
i would think 2 centimeter
Step-by-step explanation:
this would never really happen in my opinion the height and diameter would decrease. but if it takes 8 for 4 the it should take 2 for 1 because it looks like its doubling
All you have to do, is combine like terms. Let's go through it:

Arrange it so you can easily combine like terms:

So, your answer for the sum is 1) 7x² - 10x + 2