Math masters, please come in, please help solve the problem

1, Da Gang 25, Li Hua 17

2.32 tons.

3 7 (3 x 4 - x 6) = 8 solution x = 32320 kg.

7x 10-x 2) = 16-12 to get x = 20

1. Da Gang and Li Hua are not equal in age, it is known that when Da Gang is as old as Li Hua, Li Hua is only 9 years old, and when Li Hua is as old as Da Gang, Da Gang is 33 years old. How old are Qiu Dagang and Li Hua this year?

Solution: (33-9) 3=8 (years).

8 + 9 = 17 (years).

17 + 8 = 25 (years).

1. Solution: Set this year Xiaohua is x years old, and Da Gang is y years old.

From the meaning of the question, it can be obtained: x-(y-x)=9 y+(y-x)=33 solution: x=17 y=25

Answer: 2. Set the original x tons of crushed stone.

From the meaning of the question: ( 3 4) x - (1 4) x (2 3) (3 7) = 8 solution: x = 32

Answer: 3. Solution: Set the oil weight x kilograms.

From the meaning of the question: (70 100) x-(50 100) x = 16-12 solution: x = 20 Answer:

9 17 25 33 (there should be 4 data, minimum 9, maximum 33, the difference between each adjacent 2 numbers should be equal).

Li Hua is 1 year old and 25 years old.

1st time: 1 4 2nd time: 1 4 * 2 3 = 1 6 3rd time: (1-1 4-1 6) * 4 7 = 1 3

Original: 8 (1-1 4-1 6-1 3) = 32t Oil weight: (16-12) (70%-50%) = 20kg

1.Da Gang is 24 years old, Li Hua is 15 years old; 2.16 tons of crushed stone; 3.There are 20 kg of oil. (Check it yourself, o (o thank you).)

a7 0, a7 + a8 0, then a8 0, the first 7 terms and the maximum, the maximum n value is 7

X people in the class. Three-fifths x+4 = five-sixths (x+4).

Did you make a mistake?

One. 1) BC and AB1 are parallel.

From the question, ABC is an isosceles triangle, the angle C>60, know that AC is the short side, and after rotation, it will fall on BC to meet the meaning of the question C1.

As shown in Figure 1, the resulting diagram [long lines are auxiliary lines perpendicular to each other, and the intersection point o] can be obtained that angles 1, 2, 3, and 4 are all equal.

According to the parallel edge principle, since angle 2 = angle 4, BC and AB1 are parallel.

2) Same as above, parallel relationship.

3) The angle C<60, then AC is the long side, and C1 is on the extension line of CB after rotation.

The same as above, we can find ac1=ac, and we get that angle 2 = angle 3 = angle 1 is the sum of the inner angles of the triangle = 180, and the angle 4 = angle 5 can be obtained

BC and AB1 are still parallel, and the above conclusion continues to hold two. 1) According to the title, all people or fields must use it, then: x 2 + y 3 + (50-x-y) 4 = 20

The relationship is obtained: 3x+y=90

2), w=1100*x+750*y+(50-x-y)*600 gets: w=500*x+150*y+30000 substituting into (1) formula, w=71500+50*x (0<=x<=50)3) From the above formula, it can be seen that the larger the x, the higher the output value, but at the same time, the problem requires that people and fields can not be idle, then.

And because y=90-3x, (0<=y<=50) obtains: 0<=x<=30, so the output value is the largest when x=30.

30 acres of vegetables, 0 acres of tobacco and 20 acres of wheat, with an output value of 73,000 yuan.

Three, <>

(a-3)2 + square of a-b-1 + c under the root number -5 = 0

Get a = 3 c = root number 5

b = 2 acute triangles.

There are 112 in total, and if 0 is not included, the three numbers from small to large can be:

234,246,258,345,357,369,456, 468,567, 579,678,789, a total of 16 groups, each group can form 6 three-digit numbers, a total of 96.

If it contains 0, then 0 must not be in the hundreds, and the other two numbers are doubles.

There are four groups of 12, 24, 36, and 48, and the combination of 0 can form 4 three-digit numbers per group, for a total of 4*4=16.

So there are 96 + 16 = 112 in total.

1. Derivation of f(x) yields 2x+1 x-a>0, and knows a" or = 3 according to the range of values of x

2. According to the conclusion of one, according to the value of a, a<0, a is in [0, 3], the positive and negative intervals of the g(x) derivative are discussed, and the extreme value is obtained

2 root number 5 3 2 root number 5 divided by 2

Over-elliptical focal rays are reflected on the elliptical plane, and the reflected rays are over-focused.