If we know that AB is a coprime number and 9A + 18B is the square of a number, how many pairs of numbers can a and B take The surface area of a cube is 384 square decimeters. Divide the cube into 64 equal small cubes. What is the surface area of each small cube? 3. A project with 14 workers can be completed in 12 days. How many more people will be needed if it is to be completed in the first four days

If we know that AB is a coprime number and 9A + 18B is the square of a number, how many pairs of numbers can a and B take The surface area of a cube is 384 square decimeters. Divide the cube into 64 equal small cubes. What is the surface area of each small cube? 3. A project with 14 workers can be completed in 12 days. How many more people will be needed if it is to be completed in the first four days

1）
9 (a + 2b) is the square of a number, because 9 is the square of 3, so a + 2b is the square of a number
It can take innumerable pairs, such as (1,4) (1,12), (1,24)
2) It is divided into 4 × 4 × 4 cubes
You need to cut three knives in each of the three directions
Three times the original surface area
Four times the original surface area
384 × 6 = 2304 square decimeters
(you can also calculate the area of a face of a cube, divide it by 16 to get the area of a face of a small cube, and then get the area of 64 small cubes.)
3) If one person completes one copy in one day, there will be a total of 14 × 12 = 168 copies
Now it takes 12-4 = 8 days to complete
168 △ 8 = 21 (person)
Need to add 21-14 = 7 people