Travelers stay in the hotel equation, urgent! Math problems

Solution: Set up 2, 3, and 4 person rooms to rent x, y, and z rooms.

x+y+z=7 ┅┅1)

2x+3y+4z=20 ┅┅2)

2)-(1)*2 obtains: y+2z=6 z=3-y 2Because x,y,z are positive integers, y=2 or y=4

When y=2, z=2, x=3

When y=4, z=1, x=2

The calculation shows that both of them are in line with the topic.

3 for 2 people, 2 for 3 people, 2 for 4 people

Let abc, a+b+c=7

2a+3b+4c=20

a>=1

b>=1

c>=1

Among them, the b in the 3 people must be even. Because the total number of people is an even number, and 3 is an odd number.

If each type of room is rented in x, y, and z rooms, then x+y+z=7 2x+3y+4z=20 x,y,z are all positive integers, so x=3,y=2,z=2This kind of problem is to list the equation relationship of the relevant equation according to the known, and consider whether there are any constraints, and combine these to solve the equation.

Hope it helps.

There are 2 people in the room, 3 people in the room, and 4 people in the room.

Then there is 2x+3y+4z=20 (total number of people).

x+y+z=7 (total number of rooms).

However, the equations listed in this problem according to the known conditions are not enough to solve, and there is more than one solution in the first place.

The equations are based on known conditions, and these two equations are based on the total number of people and the total number of rooms.

They each ended up spending 10-1=9 yuan, that is, a total of 9 3 = 27 yuan.

The 27 yuan includes the 25 yuan that the boss got + the 2 yuan hidden by the waiter = 27 yuan.

In addition, the three of them each got back 1 yuan 3 = 3 yuan, which is exactly 30 yuan.

The 2 yuan that Lu Xiao took was included in the 27 yuan, which was the money they paid, not the money they took back!

Room x for 2 people, room Y room for 3 people, room Z room for 4 people.

x+y+z=a total of several rooms for three types of rooms.

x>=1

y>=1

z>=1

There are 2 people in the room, 3 people in the room, and 4 people in the room.

Then there is 2x+3y+4z=20 (total number of people).

x+y+z=7 (total number of rooms).

However, the equations listed in this problem according to the known conditions are not enough to solve, and there is more than one solution to this problem.

The equation is based on known conditions, and these two equations are based on the total number of people and the total number of rooms.

Solution: Set up 2, 3, and 4 person rooms to rent x, y, and z rooms.

x+y+z=7

2x+3y+4z=20

2)-(1)*2 gets: y+2z=6

z=3-y/2

Because x, y, z are.

Zhengyuanfeng rectified which number.

Therefore y=2 or y=4

When y=2, z=2, x=3

When y=4, z=1, x=2

The calculation shows that both of them are in line with the nuclear crack code of the topic.

Solution: There are x cars.

Cargo weight = cargo weight, so it is possible to not empty the inequality according to the last car dissatisfaction. Burying.

If the last reed truck is full, the goods are overcounted; If the last one is empty, the cargo is noisy or undercounted.

That is, more than the last car without 8 (x-1) and less than the last car with 8x.

So you can column: 8(x-1)<4x+20<8x5 because x is an integer, so x=6