Grade 7 Lower Mathematics Unit 3 Solving Questions

17. (1) Percentile 5 (2) 10,000 percentile 3 (3) thousandth 5 (4) percentile 5 (5) thousandth 4 (I'm a little dizzy about the exact digits, it's best to find a few more people to verify whether it is correct).

18. (1) Multiply ten by the 5th power).

19. (1) multiply ten by the minus six power (2) 8 times ten to the minus eighth power (3) multiply ten by the minus four power of ten (4) 3 times ten to the minus twelve power.

2) You can do it yourself.

Let the waist of the isosceles triangle ABC be AB and AC, if the two small triangles divided into the triangle row ABC from the straight line at point A are isosceles triangles, then there is 1 2A=B=C, and B C (the degree of each angle is represented by letters) and there is A+B+C=180 to solve A 90, B C 45

If the two small triangles divided into the trigonometric row ABC from the straight line of point b or point C are isosceles triangles, then there is C 2a, and there is a + b + c = 180 to solve a 36 and b c 72

So the degrees of each inner angle of the triangle ABC may be [45 degrees, 45 degrees, 90 degrees] or [36 degrees, 72 degrees, 72 degrees].

A passenger ship departed from Chongqing at 11:00 on August 30 and arrived in Wuhan at 17:00 on September 1. The distance from Chongqing to Wuhan is 1,354 kilometers. Excluding the 6 hours of stopping at the pier on the way, how many kilometers does this passenger ship travel about every hour?

Answer: The time difference between 11:00 and 17:00 is 30 hours.

The algorithm for the time difference is as follows:

24-11=13 (hours).

13+17=30 (hours).

30-6=24 (hours).

1354 24 = 56 (km) (rounded to the nearest decimal place).

A: The first passenger ship travels about 56 kilometers per hour.

1 All I give you the standard correct answer:

3.Solution: Let the first number be x, then the second number is 100-x, then.

x+3=100-x-3

x=47,100-x=53

4.Solution: If you want to ride x kilometers per hour, then x*1=

x=15.5.Solution: If grandpa wins x, then x=3(8-x), x=6,8-6=2

6.If it takes x hours for two people to cooperate, then (1 8 + 1 6) x = 1 x = 24 7

7.If this wheat field has x hectares, then 25%x+20%(x-25%x)+6=xx=10

8.(1) Let the age of his death be x years old. then x 6 + x 12 + x 7 + 5 + x 2 + 4 = x, x = 84

1/6x+1/12x+1/7x=33.

9.If the original price of one piece of clothing is X yuan and the original price of the other piece of clothing is Y yuan, then x(1+25%)=60, y(1-25%)=60, x=48, y=80, (48+80)-60*2=8

Lost 8 yuan. 10.The place of encounter is set to be X kilometers away from place A. Then *60=200-x 90, x=80

Supplementary Questions:

Let the father's age be 4 times the son's age after x, then 40+x=4(13+x), x=-4

A: No way.

1. Multiple choice questions (3 points per question, 15 points).

2 Wang Jing asked the teacher's age, and the teacher smiled and said, "The sum of our ages is 51, and my age is 3 times your age, 1"Can you use what you've learned to find out the ages of both of them? （

a 13 and 38 years old b 14 years old and 37 years old.

c 15 and 36 years d 12 and 39 years old.

3 On Sunday, Xiaohong and her classmates walked to the countryside at a speed of 5 kilometers and hours, and after walking for 16 minutes, her mother found that Xiaohong did not have a camera, so her mother chased Xiaohong at a speed of 13 kilometers and an hour

a 10 hours, b hours, c hours, d 6 hours.

2. Fill-in-the-blank questions (3 points for each blank, 33 points).

1 Fill in the brackets the resulting equation to justify the absence:

1) by (2) by (

2 If the equation is a one-dimensional equation with respect to x, then m , the solution of this equation is

3 If is the solution of the equation, then a =

4 If the values of are inverse to each other, then the value of x is

5 Xinghua Shopping Mall "Eleventh" implements a 20% discount on shopping. Then the price of the product is 5 yuan, the price is yuan;

Items priced at 80 yuan are priced at RMB.

6 There is no interest tax on education savings, and the annual interest rate is, Xiaoliang's parents participated in education savings in order to prepare for Xiaoliang's college tuition of 5,000 yuan after 5 years, in order to get 5,000 yuan after the expiration of 5 years, how much should Xiaoliang's parents save? The request sets the unknowns and lists the corresponding equations.

7 If x= 1 is the solution of the equation x+a=3, then a=

8.The formula is used to express that the number in the ten digit is a, the number in the single digit is b, and the two-digit calendar positive number is .

3. Solve the following equations: (4 points for each question, 16 points for each).

1．2x+3x+4x+18=0 2． 4x-3=3x-4

3．1/2x+2=1/3-1 4． 20%+1=80%-5

How simple is it to ask? Think for yourself.

Set up a 45-seater passenger car with x 45x+15=60 (x-1) solution x=5 If you rent a 45-seater passenger car cost (5 + 1) * 250 = 1500 yuan 60-seater passenger car cost (5-1) * 300 = 1200 yuan So renting 4 60-seater passenger cars is the most cost-effective.

Fabric for shirts x m 4x 5=3(630-x) 5 Note: Since the ratio of the number of clothes and pants is 3:4, clothes multiplied by 4 equals trousers multiplied by 3