Mathematics Application Questions Please answer in detail, thank you 2 19 53 46

1) Set a 60-seater vehicle as x and the number of students as y

x*60+30=y

45*（x+2）=y

Solution: x=4 y=270

2) Rent 5 cars with 60 seats, the rent is 1500

Rent 6 cars with 45 seats, the rent is 1500

Solution: If you rent a large car x and rent a small car y, then there is a binary equation system.

60x+30=45y

x+2=y gives x=4 and y=6

60*4+30=270 (person).

The number of seventh-graders is 270.

If you rent a big car, you need to rent 5 cars, 5 * 300 = 1500 (yuan) If you rent a small car, you need to rent 6 cars, 6 * 250 = 1500 (yuan), but the car still has a vacant space to put luggage, renting a big car is reasonable, the minimum rent is 1500 yuan.

1) Set up x people in the seventh grade and rent Y buses.

x=60y+30 ①

x=(y+2)45②

Get: 60y+30=(y+2)45

60y+30=45y+90

15y=50

y=4, so x=60*4+30=270 (person) 2) Set up a rental of 45 seats A and 60 seats B.

45a+60b=270

3a+4b=18

a=(18-4b)/3

So when b = 3, a = 2

3 * 300 + 2 * 250 = 1400 yuan.

Therefore, if you rent 3 cars with 60 seats and 2 cars with 45 seats, the minimum rent is 1400 yuan.

1) There are x students and rent 60-seater buses.

60y+30=x

45(y+2)=x

Solution: x=4, y=270Answer: The number of seventh-grade students is 270.

2) 45x+60y=270 Then try the list!

y=6,x=2 is the most suitable, 6·300+2·250=2300 (yuan) set up to rent 2 45-seat passenger cars, 60-seat passenger cars 6 is the most reasonable, the minimum rent is 2300 yuan.

I'm a new junior high school, we haven't learned the binary equation yet, it seems that we only learned it in the second year of junior high school, in fact, the unary equation can also be solved:

1. >: 60-seater buses are rented for x, and 45-seater buses are rented (x+2).

From the title: 60x+30=45(x+2).

Solution: 60x+30=45x+90

60x-45x=90-30

15x=60

x=4x+2=4+2=6

A: There are 270 students.

2> 60-seater bus: 300 * (4 + 1) = 300 * 5 = 1500 (yuan) 45-seater bus: 250 * 6 = 1500 (yuan).

A: The rental price of both is the same, compared to the big one, because there are more locations, and you can also put some luggage.

1) Solution: set: car y.

60×y+30=(y+2)×45

60×y=45y+90-30

60y-45y=60

15y=60

y=460 4+30=270 (person).

2) 300 (4+1) = 1500 (yuan).

250 (4+2)=1500 (RMB).

Solution: Let's rent X cars.

60x=30=45(2+x)

solution, we get x=4

4 * 60 + 30 = 270 people.

First set the amount of oil used to reduce by x kg, so the amount of oil used is 90-x kg, and then according to the "lubrication oil consumption decreases by 1 kg, the reuse rate of oil consumption will increase, and the reuse rate of oil will be (60+, so there is.

90-x)*[1-(60+

x-90)*(x-25)=750

x 2-115x+1500=0, we get x=100 or x=15, obviously x=15, so, the amount of oil used is 75 kg, and the reuse rate of oil is 84%.

The oil volume is 75kg, and the oil repeat profit margin is 84%.

(90-x)*[1-(60+

x-90)*(x-25)=750

x 2-115x+1500=0, we get x=100 or x=15, obviously x=15, so, the amount of oil used is 75 kg, and the reuse rate of oil is 84%.

1 Set x pens.

x=120 purchase price: yuan).

2. Set the length to xcm and the width to ycm

It was added by the first time.

8*8+8x+8y=384

x+y=40

The second increase from the original was.

8+8)*(8+8)+16x+16y=256+16(x+y)=256+16*40=896

The second time it was added again.

If you don't know, just ask me again.

1.Solution: Let this batch of fountain pens have x branches.

x=120,120*RMB).

Answer: The ** of the store to buy this batch of fountain pens is more than one per pen.

2.((384-8*8) 8+16)*8+8*8=512 (square centimeters) Answer: The area will increase by another 512 square centimeters.

Solution: The ** of this batch of fountain pens is each x yuan, and there are a total of y.

Solution: x=y=120Answer: The purchase price is yuan.

Question 1:

Passing B to do the perpendicular line of AC BC

bac=30° ab=20*16=320∴bc=320*1/2=160

Point B will be affected.

The second question is to unload the cargo in time for point B, when it is on the edge of a typhoon.

bc=160

cd=120 (Pythagorean theorem).

again ac= 3bc = 160 3

ad=160√3-120

When the center of the typhoon moves from A to D, point B must complete unloading.

t=ad/40 =4√3-3≈

So it is necessary to complete the unloading within 4 hours.

There are pictures and wait.

Draw a picture of yourself When the shortest distance of the straight line from point B to the typhoon is vertical, the angle at this time a = 30 degrees, so the straight line distance from b to the typhoon is 1 2 of the ab distance, that is, 1 2 * 20 + 16 = 160 nautical miles, because it is 200 nautical miles from the center of the typhoon that is affected, so it is within the range of influence.

The second question is not easy to explain, let me tell you the method, you find a little p in the straight line of the typhoon, the distance from p to b is 200 mass, then point b will be affected, that is to say, to unload the goods in this time, b to the straight line of the typhoon as a perpendicular line, the perpendicular point is c, this distance is 160, that is, bc = 160 nautical miles, find the value of cp in the right triangle bpc, and then use ac-cp = ap, that is, the distance traveled by the typhoon, there is speed, you can find the time, This time is also the time when the goods will be unloaded.

If you don't understand it, just ask me online.

Look at whether the triangle is an obtuse triangle or an acute triangle, and who minus who sets the waist length to 2x

Then there are two cases, either 3x-(x+10)=2 or (x+10)-3x=2

The waist length is or 8

Set the waist length to 2x

Then there are two cases, either 3x-(x+10)=2 or (x+10)-3x=2

The waist length is 2x and it is either 12 or 8

8 or 12

Because two triangles are the same length as two sides. One is the midline and the other is half the waist length. The bottom edge is 10, so the waist length is 8 or 12

Solution: Let's say he originally had an x-yuan.

x ÷ 2 - 5×5 = 100

x = 250

A: Initially he had $250 with him.

250 yuan.

The five attractions cost a total of 25 yuan

The remaining 100 yuan is half of the 125 yuan

So I brought 250 yuan