5.x and Y represent two numbers. Specify a new operation? *? And then what? △? As follows: x*y=mx+ny, x△y=kxy, where m, n and k are natural numbers. Given that 1*2=5, (2*3)△4=64, find the value of (1△2)*3.
Chapter III Units of Measurement
First, thinking before review:
1. As we all know, in mathematics, 2 >: 1,1000 <; 1000. 1, but the following says
1 & gt； 2 、 1 = 1000
Do you think they are right or wrong? Tell me your reasons.
2. In idioms,? Half a catty? What does this mean?
( 1)? Half? What is it in numbers? In this idiom, why can you think of it? Eight? What about equality?
(2) In today's view, how many ounces should half a catty equal?
Second, the unit of measurement review:
So far, we have learned many units of measurement. Do you know which ones?
1. Length units: meters, centimeters, decimeters, millimeters, kilometers, kilometers and miles.
2. Time unit: year, month, day, hour, minute and second.
3. Weight unit: kilograms, grams, tons, kilograms and kilograms.
4. Area unit: square meters, acres and hectares.
5. unit of volume: cubic meters, liters
Third, the conversion between units:
1. Length unit:
2. Time unit:
3. Weight unit:
4. Area unit:
5. unit of volume:
Fourth, practice (time standard: 7 points/section):
A
1, and fill in the appropriate company name in brackets.
1. A bag of rice weighs 40 ().
2. The length of the desk is 86 (), and the area of the desktop is about 54 ().
3. The car runs every hour 100 ().
A thermos can hold about 2.5 () of water.
5. A building is 15 () high and covers an area of 600 ().
6. Xiaoming spent 20 pounds on a meal.
2. Fill in the appropriate numbers in the brackets.
①3 km = () m 3 cm = () mm
②4 square meters = () square decimeter = () square centimeter
③ 3.05t = () kg = () g。
④4 days = () hours = () minutes
⑤6 decimeters = () meters 50050 meters = () kilometers.
6.20 square centimeters = () square meters 3.3 hectares = () square kilometers.
⑦ 1.7 liter = () cubic meter = () cubic centimeter.
3. Fill in the appropriate numbers in brackets.
(1) 3 km 8 m = () m 4 m 2 cm = () cm
②43 square meters 120 square centimeters = () square decimeter.
③8 tons and 300 kg = () kg
④5 days 18 hours = () hours 9: 30 = () minutes.
⑤45.8 decimeter = () meter () decimeter () centimeter.
⑥47055 cubic decimeter = () cubic meter () cubic decimeter
⑦ 10200kg = () tons () kg.
830 months = () years () months 830 seconds = () minutes () seconds.
There are four quarters in a year, and every three months is a quarter. Q: How many days are there in each quarter?
5. Xiaohua walked 4500m, and it took 1 hour and 15 minutes. How many meters per minute on average?
B
1, and fill in the appropriate company name in brackets.
1. An adult weighs about 65 ().
2. Xiaoming rides a bike every hour 12 ().
3. A penny is 1 () thick, and the area of a stamp is 6 ().
4. A pencil is 18 ().
5. The time of a class is about 45 ().
6. A barrel can hold about 25 () of water.
2. Fill in the appropriate numbers in the brackets.
① 5.05km = () m 12cm = () mm。
124.2cm = () m1791decimeter = () km.
② 1.2m2 = () square decimeter = () square centimeter.
③3 tons = () kg = () g.
1422g = () kg = () kg
④ 6th = () hours = () minutes
1 average year = () days = () hours
⑤ 160 decimeter = () m 5 1000 m = () km.
⑥ 120000 square centimeter = () square meter = () square decimeter.
All landowners 330000 hectares = () square kilometers.
⑧360 seconds = () minutes 72 hours = () days
1 year = () days = () hours
3. Fill in the appropriate numbers in brackets.
①3 m2 1 m2 23 m2 = () m2
②6 km18m = () 3m 12 decimeter = () cm.
③5 tons12 kg = () kg = () g.
④7 days and 8 hours 12 points = () points.
7 days 12 minutes = () hours
⑤648 cm = () m () decimeter () cm
⑥4760.5 cubic decimeter = () cubic meter () square decimeter () cubic centimeter.
⑦ 90500kg = () tons () kg.
254 1.09 kg = () tons () kg = () grams.
81month = () year () month 742 seconds = () minutes () seconds.
The fourth chapter geometry knowledge
There are four types of geometry problems: 1. Judgment and analysis of concepts; 2. Find the length (side length, side length, perimeter, diameter, arc length); 3. Find the area (surface area); 4. Find the volume.
The first section to judge right or wrong
Typical example:
1. A quadrilateral with four equilateral sides is a square.
2. A figure composed of three line segments must be a triangle.
3. An equilateral triangle is an isosceles triangle.
A quadrilateral whose four corners are right angles is a square.
5. Two opposite sides of a parallelogram are parallel.
6. Light can extend to any direction indefinitely.
7. As shown in Figure 3- 1, straight line AC> straight line AB
8. A figure composed of two line segments with common endpoints is called an angle.
9. The degree of complementary angle is less than that of complementary angle.
10. Every face of a cuboid is a rectangle.
1 1. Knowing the height of one side and one side of a triangle, we can calculate its area.
12. The areas of two sectors with equal perimeters must also be equal.
13. The larger the arc, the larger the sector area.
14. The radius of the big circle is the diameter of the small circle, and the area of the big circle is twice that of the small circle.
15. The arc length of a semicircle is the circumference of a semicircle.
Second, consolidate the exercises:
1. The circumference of the circle is reduced by 1/2, the diameter by 1/2, and the area by 1/2.
2. The size of pi varies with the area of the circle.
1. What courses do junior high school students in Shandong have?
The current junior high school courses are:
Grade one: Chinese, math, Eng