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1,4a 2-4ab 3+b 2 92,b4, let the side length of the flower bed be x, then the length of the field is (x+8), the width is (x+6), so, (x+8)(x+6)-x 2=104 is obtained by x=4, so the length is 12, and the width is 10

5, multiply both sides of the equation by 2 to get 2a 2+2b 2+2c 2-2ab-2bc-2ac=0

That is, (A2-2Ab+B2)+(B2-2B+C2)+(A2-2AC+C2)=0

a-b) 2+(b-c) 2+(a-c) 2=0So, a-b=b-c=a-c=0

a=b=c, so it's an equilateral triangle.

4a²-8/3ab+b²/9

B4 set the length of the flower bed is a, then (a + 8) (a + 6) -a = 104 then 48 + 14a = 104, a = 56 14 = 4 then the length is a + 8 = 4 + 8 = 12, the width is a + 6 = 105 because a + b + c = ab + bc + ca, then the two sides are multiplied by 2.

2a +2b +2c -2ab-2bc-2ca=0 then (a-b) +a-c) +b-c) =0 then a=b=c

So the triangle ABC is an equilateral triangle.

1. The outer diameter is 2m 5=, and the inner diameter is 2m5=.

One piece weighs: 1000 pieces weigh kilograms.

2. The volume is equal to the volume of the drained water: cubic centimeters.

3. Cut parallel to the bottom surface, increase the two bottom areas for each cut twice, a total of 4 bottom areas, so the diameter x diameter 4=, diameter = 4 cm.

Add two diameters x heights along the diameter cut, so diameter x height = 40 2, and therefore higher than 5 cm.

So the volume is equal to cubic centimeters.

1.π*

2.π*20^2/4*2=628cm^3

3.Base area = , diameter = 4cm, length = 5cm, volume =

1290 180= The number of sides cannot be a decimal, it must be an integer, so it is equal to 8

The formula for finding the sum of the angles in the multi-sided row is: (n-2)*180

So the number of sides of this polygon is n-2=8 to get n=8+2=10 (edges).

Suppose C is 38 years old, and A's age is x, then B is 2x

Suppose that after y years, when B is half the age of C, A is 17 years old x + y = 17

2x+y=(y+38)÷2

x=7 y=10

Therefore, when C is 38 years old, A is 7 years old, B is 14 years old, and because the sum of the ages of A, B and C is 113

So now A is 25 years old, B is 32 years old, C is 56 years old.

Let A x B y C Z

There is x+38-z=2*(y+38-z).

y+17-x=2*（z+17-x）

x+y+z=113

The answer can be solved.

A, B, C.

1、 x 2x 38

2、 17 y 2y

17-x=2y-38 x=55-2y

y-2x=2y-38 y-110+4y=2y-38 y=24 x=7

Therefore 7 14 38

17, 24, 48 and 89

B is 32 years old.

Let A, B, and C now be x, y, and z years old.

x+y+z=113，①

When A is half the age of B, C is 38 years old: x+a=(y+a) 2, z+a=38

a=38-z

x+38-z=(y+38-z)/2

2x-y-z=-38 ②

When B is half the age of C, A is 17 years old: y+b=(z+b) 2, x+b=17

b=17-x

y+17-x=(z+17-x)/2

x+y-z=-17 ③

②：3x=75

x=25z=40

y=48

Let's say that C is 38 years old, and A's age is x, then B is half the age of C and A is 17 years old.

x+y=17 ..1）2x+y=(y+38)÷2...2) (1) arrangement.

x=17-y ..3) (3) substitution (2) obtained.

2（17－y）＋y＝（y＋38）÷2

Y 10 substitut y 10 into equation (1).

x 7 C 38 years old B 7 2 14

113 [(38 7) (14 7)] 7575 3 25 (A is of current age).

18 14 32 years old (B current age).

18 38 56 years old (C current age).

4*3*2*1 kinds.

This is the permutation question, and the answer is 4!

1. Solution: Let the distance between ab be x, and according to the question, (x-36) 2 times 4=x+36

x=108A:.

2. Solution: Let A x days, B y days, according to the title, get {4x+8(x+y)=840

4y+9（x+y）=840

12x+8y=840①

9x+13y=840②

From , x=(840-8y) 12=(210-2y) 3 substitutes x=(210-2y) 3.

210-2y) 3 times 9 + 13 y = 840y = 30

Substituting y=30 into to get.

12x+240=840

x=50A,。。

3. According to the title, substituting any number 0 and 1 into it, then when x=0, ax-3+5x+a+b=0

3+a+b=0

a+b=3When x=1, ax-3+5x+a+b=02a+b =-2

This yields { a+b=3

2a+b =-2②

Get. a=-5

Substituting a=-5 into , gets.

b =8A,。。

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The distance between the two places is 108 km. As can be seen from the question, because it took 2 hours for A and B to be 36 kilometers apart for the first time and 36 kilometers for the second time, it can be seen that the two met one hour after the first 36 kilometers apart, and they each walked 18 kilometers, that is, their speed was 18 kilometers per hour, so (2 18+18) 2=108, so the distance between the two places was 108 kilometers.

2. Let A make x parts per day, and B can make y parts per day.

4x+8(x+y)=840 x=504y+9(x+y)=840 y=30 urgently, you can make 50 parts a day, and B can make 30 parts a day3a=-5 b=8