1, solution: The three sides are 156m, 186m, 234m, and the tree spacing is 6m, so there are 39 tree spacing on the three sides. Take paragraph 26 as an example, the change should be 26+ 1.

2, unable to answer

3. Let the length of the subtracted cube be a, then the volume of the folded carton = a (24-2a) (24-2a) = 4a (12-a) (12-a).

Let y=4a( 12-a)( 12-a) and y' = 4 (12-a) (12-a)+8a (12-a).

Let y'=0, then the maximum value of A is 12, the minimum value is 4, and the minimum value of Y' corresponds to a=8, then when a=

Y is the largest.

4. Find two extreme scores, one is-10 for all wrong answers and the other is -40 for all correct answers, so let's set one correct answer, b wrong answers and c no answers, and then-10 "4a-b" 40. From-10 to 40***, there are 5 1 integers, that is, there are at most 5 1 grades.

When a= 10, b=0, corresponding to 1 level 40.

When a=9 and b=0 or 1, there are two grades 36 and 35.

When a=8 and b=0 or 1 or 2, there are three grades 32,3130.

When a=7, b=0 or 1 or 2 or 3, it corresponds to four grades of 28, 27, 26 and 25.

5 1 minus the digits not involved, there are 45 kinds of * * *.

……

By analogy, the value of (10-a) is+1, which is the number of values that B can take, so 1+2+... 10.