Using equations to solve practical problems, Pour the water in the cylindrical bucket with an inner radius of 20cm into another small cylindrical bucket until it is full. The inner radius of the small cylinder is 10cm, and the height is 15cm. When the small bucket is full of water, how much does the water surface of the big bucket drop? Let the distance between the water surface of the big bucket and the opening be xcm

Using equations to solve practical problems, Pour the water in the cylindrical bucket with an inner radius of 20cm into another small cylindrical bucket until it is full. The inner radius of the small cylinder is 10cm, and the height is 15cm. When the small bucket is full of water, how much does the water surface of the big bucket drop? Let the distance between the water surface of the big bucket and the opening be xcm

The water level of the bucket dropped HCM
According to the meaning of the title:
202＊π＊h﹦102＊π＊15
The solution is h = 3.75
A: the water level of the bucket has dropped by 3.75cm

75%X+（2400-X）*55%=2400*60%

75%X+（2400-X）*55%=2400*60%
75%x-55%x=2400*(60%-55%)
0.2x=120
x=600

The decomposition factor ax ay + X & # 178; - Y & # 178; is solved

=a(x-y)+(x+y)(x-y)
=(a+x+y)(x-y)

8 minus the quotient of 4.6 divided by 2.3, what is the product of the difference multiplied by 6?

（8-2.3÷4.6 ）×6
=（8-0.5）×6
=8×7.5
=60

With a 72 cm long wire, it can be welded into a rectangular teaching aid with a length of 8 cm, a width of () cm and a height of 4 cm
With a 72 cm long wire, it can be welded into a rectangular teaching aid with a length of 8 cm, a width of () cm and a height of 4 cm

(72-4 × 8-4 × 4) △ 4 = 24 △ 4 = 6cm

Arrange the remainder of 1,2,3,4 divided by 3 to get a sequence. What is the sum of the first 100 numbers in the sequence?

After N divided by 3, the characteristics of the sequence are: 000,1,2,0,1,2,0,. 1, so the sum of the first 100 is 3 * 32 + 1 = 65

The first n terms of known sequence {an} and Sn = n & # 178; - 9N (1) for an

When n = 1, A1 = S1 = 1 & # 178; - 9 × 1 = 1-9 = - 8
When n ≥ 2, an = SN-S (n-1) = n & # 178; - 9N - [(n-1) &# 178; - 9 (n-1)] = 2n-10
When n = 1, A1 = 2 × 1-10 = - 8, which also satisfies the general formula
The general formula of sequence {an} is an = 2n-10

Verification: Zero nine cycle equals one

0.999…… =0.9+0.09+0.009+…… The latter is the sum of an infinitely proportional recursive sequence, whose sum is equal to 0.9 (1-0.1) = 1, so 0.999 =1

Factorization of B & sup2; + C & sup2; + 2Ab + 2Ac + 2BC

a²+b²＋c²＋2ab＋2ac＋2bc
=(a+b+c)²
This is the formula

There are four numbers, three of which are added each time. The sum of them is 15, 17, 19 and 21 respectively. What are the four numbers?

The sum of the four numbers is: (15 + 17 + 19 + 21) / 4 = 24
The four numbers are 9, 7, 5 and 3 respectively