2 1.
Analysis: Because the title explains that painting any face is a situation, a combination, not an arrangement.
One side of the chart-1 example
Two sides of a painting-two situations (adjacent or opposite)
Three faces in the picture-two cases (all three faces are adjacent, and two of them are adjacent)
Figure Four Faces-Two Cases (Two Faces Adjacent and Three Faces Adjacent)
Figure 5 Face-1 Case
Figure 6 Face-1 Case
So a * * *1+2+2+1+1= 9 cases.
36.
The title says that in the case of winning, a * * * has three people, which means that a * * * has three positions to participate in the election, but the title only says two positions, so there is one more.
37.
9*9+9+9/9+9
=8 1+9+ 1+9
= 100
39.
Porcupine:118 = 0.056
Coyote: 1/72=0.0 14
t 1-t2
=0.056-0.0 14
= 0.042 hours
2.5 minutes
4 1.
Analysis: According to the known formula H = 20t-5t 2, the time 1s, 2s and 3s are brought in respectively.
h 1=20* 1-5* 1^2
=20-5
= 15m
h2=20*2-5*2^2
=40-20
=20m
h3=20*3-5*3^2
=60-45
= 15m
42.
Analysis: If the sum of two numbers is required to be a complete square number, then there are 4, 9, 16, 25 * * * complete squares greater than 2 and less than 26.
4- 1+3/2+2-2 cases
9- 1+8/2+7/3+6/4+5-4 cases.
16-3+13/4+12 ... 7+9/8+8-6.
25-12+13-1example
So a * * * has 2+4+6+ 1= 13 cases.
43.
Analysis: 20 toothpicks were divided into 3 groups, each group was even.
2,2, 16
2,4, 14
2,6, 12
2,8, 10
4,4, 12
4,6, 10
4,8,8
6,6,8
***8 methods