1. The side of a cylinder is square, and the ratio of the bottom radius to the height of the cylinder is () 2. The area of the bottom of the cylinder is expanded to three times of its original height and reduced to one third of its original volume 3. The inner barrel of a washing machine is cylindrical, with a bottom diameter of 40 cm. If the height of water used each time is 25 cm, how much cubic centimeter does it take to wash three times at a time? How much water does a family need to wash twice a week?

1. The side of a cylinder is square, and the ratio of the bottom radius to the height of the cylinder is () 2. The area of the bottom of the cylinder is expanded to three times of its original height and reduced to one third of its original volume 3. The inner barrel of a washing machine is cylindrical, with a bottom diameter of 40 cm. If the height of water used each time is 25 cm, how much cubic centimeter does it take to wash three times at a time? How much water does a family need to wash twice a week?

1. The side of a cylinder is square, and the ratio of the bottom radius to the height of the cylinder is (R / h = 1 / 2 π)
Because the side spread is square, the perimeter of the ground is equal to 2 π r = H
2. The area of the bottom of the cylinder is expanded to three times of its original height and reduced to one third of its original volume
s=3s1 h=1/3h1 sh=3s1*1/3h1 =s1*h1
3. The inner barrel of a washing machine is cylindrical, with a bottom diameter of 40 cm. If the height of water used each time is 25 cm, how many cubic centimeters does it take to wash three times at a time? It is estimated that how much water does a family need to wash twice a week?
20 * 20 * 3.14 * 25 * 3 = 94200 cm3
94200 * 2 * 52 = 9796800 cm3

There are nine students in the group, and at least two of them will participate in the same interest group. If each student can participate in three interest groups at most, how many students will participate in the same interest group?
I don't think so. There are nine people in a group! How could it be six

I think the sentence at the end of this question seems to be deceiving. If (at least 2 of any 3 of them participate in the same interest group), then at least 9 * (2 / 3) = 6, so the answer should be 6

Given that X1 and X2 are two of the equations 3x2-19x + M = 0, and X1 = m3, then the value of M is______ ．

Substituting X1 = m3 into 3x2-19x + M = 0, we can get 3 × (M3) 2-19 × m3 + M = 0, and sorting out m2-16m = 0, that is, m (M-16) = 0, M = 0 or M = 16