Answer: The volume is doubled.
Explanation:
I will answer in English.
This says that:
"The radius of a cylinder is equal to its height, what would happen to the volume of this cylinder if the radius is doubled, and the height is halved?"
The volume of a cylinder of radius R y height H is:
V = pi*R^2*H
In this case, the radius is equal to the height, then the initial volume is:
V = pi*(R^2)*R = pi*R^3
Now, for the new cylinder we will have:
Radius = 2*R
Height = R/2
Then the new volume is:
V' = pi*(2*R)^2*(R/2)
V' = pi*4*R^2*(R/2)
V' = (4/2)*pi*R^2*R
V' = 2*pi*R^3
And pi*R^3 was the volume of the original cylinder, then:
V' = 2*V
This means that when the radius is doubled and the height is halved, the volume of the cylinder is doubled.