8 math problems to do! Urgent

Solution: (1) Because OM bisects AOC and ON bisects BOC, mon=1 2( AOB + BOC)-1 2 BOC1 2 AOB + 1 2 BOC-1 2 BOC1 2 AOB

1 2*90 degrees.

45 degrees. 2) In the same way, mon=1 2 aob =1 2a3) In the same way, mon=1 2 aob = 45 degrees.

4) The rule of these three ways is: mon=1 2 AOB and has nothing to do with BOC.

5) Actually, just change the angle to a line segment. For example:

1) The line segment AB=10 cm, the line segment BC=4 cm, M is the midpoint of the line segment AC, N is the midpoint of the line segment BC, how many centimeters is the length of the line segment Mn?

Solution: mn = 1 2 (ab + bc) -1 2 bc = 1 2 ab = 1 2 * 10 = 5 cm.

2) If the line segment ab=a in the above question, other conditions remain unchanged, how long is the line segment mn?

Solution: mn=1 2(ab+bc)-1 2bc=1 2ab=1 2a3) If BC=B in 1) and other conditions remain unchanged, then how long is Mn?

Solution: mn = 1 2 (ab + bc) -1 2 bc = 1 2 ab = 1 2 * 10 = 5 cm.

4) What is the pattern of the results in the question?

Solution: The law is: mn=1 2ab

Glad for you.

1.The two teams A and B took 4 days, and they worked for two days, so 1 2 was completed, and the remaining 1 2 B was completed in 4 days. So to complete the whole project, B needs 8 days.

Therefore, B can complete 1 8 of the project per day. And the two teams completed 1 4, so A also completed 1 8 (1 4-1 8) every day. Therefore, it takes 8 days for Team A to complete it alone.

2.This question examines the greatest common divisor. Divisor of 42.

Divisor of 112.

Divisor of 70. It can be seen that the greatest common divisor is 14. Therefore, it can be divided into up to 14 piles. There are 3 Chinese books in each pile, 8 math books in each pile, and 5 English books in each pile.

3.If there are x art books, then there are 2x story books and (1 2x-1) science books. Therefore, there is x+2x+(1 2x-1)=90, and the solution is x=26.

Therefore, 26 art books were bought, 2*26=52 story books were bought, and 1 2*26-1=12 science and technology books were bought.

4.There is a total of one-half hectare of the land, a quarter of a cucumber, so that a quarter of the hectare is planted with tomatoes, i.e., tomatoes occupy 1 2 of the land. That is, a quarter hectare = 1 4 * 10,000 square meters = 2,500 square meters.

5.Cut along the face with the smallest area, i.e. the 16x8 face. Minimum increase: 3 * 8 * 16 = 384 square meters.

6.Let this number be x. From the title: x+1 10=7 15, so x=7 15-1 10=11 30. That is, this number is: 11 30.

7.Let this number be x, and get: 5 6-x=1 6+1 2. Therefore x=5 6-(1 6+1 2)=1 6.

8.Let this number be x, and you get 5x+. Therefore x=(.

1.It's all 8 days.

Heap, including 3 Chinese books, 8 math books, and 5 English books.

3.There are 52 story books, 26 literary books, and 12 science and technology books.

4.Three-quarters, 7,500 square meters.

5.Cut the 24 m side into 4 parts, and the added surface area is the smallest, and the increased surface area is 8*16*6=768

1/10 = 7/15, x = 7/15 - 1/10 = 14/30 - 3/30 = 11/30

x = 1/6+1/2, x = 5/6 - 1/6 -1/2 = 1/6

5x = , x =

1:a=，==

b=,a b=empty set;

2a+1<-2 or a+1 >5

a<-3/2;or A>4;

2: (1) If there are two elements in a, i.e., there are two roots, ax 2-3x-4 = 0

a≠0；=(-3)^2-4a(-4)>0

>a>-9/16;

a∈（-9/16,0）∪（0，+∞

2) If there is at most one element in a, i.e. there are two equal roots, ax 2-3x-4 = 0

When a≠0; =(-3)^2-4a(-4)=0

>a=-9/16;

a=-9/16；

When a=0, the equation is solved, x=4 3, and at most one element in a is satisfied;

a=0 or a=-9 16; ##

[Solution] 1

a===> a=

> a=

If b=, and a b= , then.

a+1>5 or 2a+1<-2.

A>4 or A<-3 2

2.(1) If the equation ax2-3x-4=0 has two roots, a≠0 and δ>0 are required, i.e., 9+16a>0 and a≠0

The solution is a>-9 16 and a≠0

2) If the equation ax2-3x-4=0 has at most one root, then a=0 or a≠0 and δ 0, i.e., 9+16a0 and a≠0 solve a -9 16

Combined: a = 0 or a -9 16

1), a in the solution of inequality gives -2 "x "5, to b, a+1 x 2a+1, so a" 0;A intersects b = empty set, then there is a + 1>5, or 2a + 1<-2 that is, a > 4 or a "rounded", so a > 4

2) There are two elements, then ax 2-3x-4 = 0, a is not equal to 0 and the equation = 9 + 16 a>>-9 16; and a is not equal to 0; At most one element, then the equation a=0, x=-4 3 or the quadratic equation =9+16a" and a=0

Is question 2 a real root, the title does not say.

The landlord still draws a number line to judge the endpoint.

1. To be conditional only.

a+3 <=4 and a >=2

Simultaneous solution: -2 <=a <=1.

2. To be valid, only need.

A < 2 or A+3 > 4

Solution: A < 2 or A > 1

3. To be valid, only need.

A + 3 < 2 or A > 4

Solution: A < 5 or A > 4

4. If the title is this cra u b = cra then it should be solved like this:

a+3 <=4 and a >=2

Solution: -2 <=a <=1

Greater than or equal to -2 and less than or equal to 1

Greater than or equal to 1 or less than or equal to -2

Less than or equal to -5 or a greater than 4

Greater than or equal to -2 and less than or equal to 1

1.-2 a, a+3 4, so -2 a 1

2.And 1 is the opposite.

Intersection b = b, i.e. b belongs to a

So A+3 -2 or A is greater than 4 (not ).

cra is a complement of a) and b=cra i.e. b belongs to cra, so -2 a a+3 4 so -2 a 1

You can see that 1 km is several times that of 2 3 km: 1 (2 3) = 3 2 So 1 km consumes fuel: 3 2 * 2 25 = 3 25 Question 2 In the same way, 1 liter of oil is several times that of 2 25: 1 (2 25) = 25 2

Therefore, 1 liter of oil can do: 25 2*2 3=25 32, according to the title, 4a=b5 2=3c

So a=3c4 aa=5b 8 ac=5b6c, so a

The fuel consumption per kilometer is (2 25) (2 3) = 3 25, and 1 liter of oil can travel 25 3 kilometers.

i.e. 4a = and, obviously, b>c>a

Question 1: To know how much water is in the cup, how much water is less in the test tube. The inner diameter (meaning diameter, which is 2 times the radius) is 8 and the radius is 4.

When the cup is full, the volume of water in the cup v = 4, which is the volume of less water in the test tube. v test less = 3 h, that is, 9h = 16, find h=.

Question 2: I don't understand the meaning of the question. According to my understanding, the inheritance of the eldest and the second is equal, assuming that the total inheritance is Y.

The inheritance of the eldest is 100+(y-100) 10=90+, and the inheritance of the second is 200+[y-(90+. If the inheritance of the eldest and the second is equal, then 90+ = 191+, and the calculation can obtain y=10100.

Question 3: 1 (a+b) a

0 a/b b

These three numbers can be realized into the above two forms, and the evolution is that the second number on the top is divided by the second number on the lower side, and the third number on the top is divided by the third number on the bottom side, and the formula (a+b) (a b) = (a b) can be obtained by multiplying the diagonal lines to obtain the formula (a+b) b = a a b), that is, a b + b = b, that is, b + (a-1) b=0. Find b=0 and a=1. Just as it fits.

Question 4: If you look at it, there is a certain pattern of subtracting the number after a number, that is, the number after it is 3 times that of it. If you see the pattern, you can change the formula to this.

Question 5: Do you mean ? If so, you can solve the problem like this: =, =10 = 100 =.

It's late, and it's definitely not scored. Let's forget about the 2 questions.

Let the total amount of money be x, the eldest takes 100 + 1 10 (x-100), and the second takes 200 + 1 10 (x-(100 + 1 10 (x-100)))-200).

So 100+1 10(x-100)=200+1 10(x-(100+1 10(x-100))-200).

The total amount of money is 8100, and then you can calculate that each person is 900, a total of 9 people.

First course:

2nd lane: 8100 CZK 9 children 900 CZK each 3rd lane: 2001 power of A plus 2002 power of B 1th lane: -2 (17*33).

Fifth way: square = (square = squared=

B, link AC

Demonstrate abc=90° bc=ba=2 bac=45° ac=2 2

and ad=1, dc=3, ac squared + ad squared = dc squared.

cad=90°

dab=135°

Select B, connect A and C, and obtain AC=2 2, BAC=45°;

From the Pythagorean theorem, cad=90°, so dab=135°