Ask for the solution of junior high school mathematics masters, and the system of inequality equatio

Solution: If the number of people who go to the school to participate in the spring outing is A, then there is.

A 45 = (A+30) 60 +1, solution: A=270 set to rent 45 passenger cars x, then rent 60 passenger cars (x+1), by the title.

If you need to rent a 45-seater passenger car separately 270 45 = 6 cars, the rent is 250 6 = 1500 yuan, if you need to rent a 60-seater passenger car separately (270 + 30) 60 = 5 cars, the rent is 300 5 = 1500 yuan, then there are:

250x+300(x+1)＜1500

45x+60(x+1) 270, solution: 2 x (24 11 )x is a positive integer x=2

That is, rent 2 45-seat passenger cars and 3 60-seat passenger cars, at this time, the rent is: 250 2 + 300 3 = 1400 (yuan).

So the answer is 270, 1400

If the number of 45 passenger cars is x, then 45x=60(x-1)-30 x=6 The number of people participating in the spring outing is 6x45=270 people.

2 If you rent x 45-seater cars, then 60 seats x +1

45x+60(x+1)=270 so x=2, the rent is 250x2+300x3=1400

1.Solution: Let A make x parts per hour, and B make y parts per hour, which is derived from the question: 4y-(

A made one on this day, and B did 464 on this day.

2.Let the distance of the AC section be X km, and the distance of the BC section is Y km, which is derived from the title: x 20 + y 40 = 3

y/20+x/40=

2y+x=180

Solution: x=20 y=80

1. Solution: Let A make x parts per hour, B make y parts per hour, according to the meaning of the problem, the system of equations can be listed

4x-(240+40)=4y

Solve this system of equations.

x=128，y=58

Then the number of parts made by A in one day is (, and the number of parts made by B in one day is 8y=464.

2. Solution: Let the distance of the AC section be X kilometers and the distance of the BC section be Y kilometers. According to the meaning of the question, a system of equations can be listed.

x/20+y/40=3

y/20+x/40=

Solve this system of equations.

x=20，y=80

1.A produces x pieces in one hour, and B produces Y pieces in one hour. ((

x=128 y=58

A made 704 parts B made 464 parts 2The distance between x is y

x/20+y/40=3

x/40+y/20=

x=20 y=80

The distance between them is 20 km and the distance between them is 80 km.

1: Let A make x a day, and B make y a day.

then x-y=240

y/2-x/(

The solution is x=704 y=464

2: Set ac=x cb=y

then x 20 y 40 = 3

x/40＋y/20=

Solution: x=20 y=80

1.In the afternoon, A made a total of 240 + 40 = 280 parts more than B, 280 4 = 70 parts per hour, and A made one more part than B in the last hour of the morning, and B did a total of 105 + 40 = 145 parts in the previous hour, and B's speed was 145 parts per hour, and a total of 58 * 8 = 464 parts were made in a day, and A made a total of 464 + 240 = 704 parts.

2.Let the AB distance be X km, the car round trip AB is equivalent to going uphill for X km, and downhill for X km, that is, x 20 + x 40 = 3+, the solution is x = 100, and then let the ac distance be y km, and get y 20 + (100-y) 40 = 3, and the solution is y = 20, that is, the AC distance is 20 km and the BC distance is 80 km.

Let A do x per hour and B make y per hour.

4y- (solution x=128, y=58.)

A did 128 * ( in one day, B did 58 * (4 + 4) = 464 in one day, and set AC section xkm and BC section YCM

x/20+y/40=3

y/20+x/40=

The solution is x=20 and y=80

【Analysis】The solution set of the inequality group {x+15x3+x-24 is obtained by x, and then expressed by the number line, the solution set of the inequality group can be known.

1. Multiply both sides of the solution inequality x+15 by 5 to obtain.

x+1 move items, organize, get.

2x gets the solution of x inequality 2x-23>x3+x-24, multiplied by 12 on both sides, and obtains.

4 (2x-2) > 4x+3 (x-2), remove the parentheses, get.

8x-8>4x+3x-6, move items, sort, get.

x>2.

The first one, because 5 is the denominator, is equivalent to, x 1 3 x. Knot x 1The same goes for the second. The first denominator is divided into all variable 12, and the numerator can be equivalent to 8x 8 4x 3x 6Solution. x＞2

First pass the points, and then cross multiplication, the direction of the unequal sign remains the same.

Solution: If the price of 300 is 50% of the higher purchase price, then the purchase price is 300 (1+50%) 200 yuan, if the price of 300 is 100% of the higher purchase price, then the purchase price is 300 (1+100%) 150 yuan, so the purchase price of clothing is between 150 yuan and 200 yuan. Let our counteroffer be $x, then the inequality group can be listed as follows:

150 (1+20%) x 200 (1+20%) solves: 180 x 240

So you should make a counteroffer between 180 yuan and 240 yuan.

From the 50% and 100% of the higher purchase price, it can be seen that the purchase price of this garment is 150 200 yuan, and a 20% increase in the price can make a profit, so the counter-offer range is: 180 240 yuan.

Solve by inequality: Let the purchase price be $x, then 300-x>=, and 300-x<=x.

Solution, 150<=x<=200

So, 180 < = < = 240

The counteroffer range is 240 300.

1.1 4a square ab + b square = 1 4 (a square - 4ab + 4b square) = 1 4 (a - 2b) square.

2.Suppose it is 3x cubic 3x cubic - 12x square y + 12xy square = 3x (x square - 4xy + 4y squared) = 3x (x-2y) squared.

3.(A square + B squared) square -4a square b square = a 4th power + 4a square b square + b 4th power - 4a square b square = a 4th power + b 4th power.

squared - 3x-2 (2x+1)(x-2).

5.x-squared-2x-8=0 (x-1) squared2 -9=0 x=4 or -3

6.4x squared - 4x=15 (2x-1) squared = 16 x=2 or - (3 2).

7.4x squared + x-14 = 0 (x+2) (4x-7) = 0 x = -2 or 7 4

8.x squared - 2x + 3 = o (x - 1) square + 2 = 0 No solution.

9. 1-2x>0 2x<1 x<1/2

10.Equations.

x-3(x-2)≥4 x-3x+6≥4 -2x≥-2 x≤1

3x-1)/5<(x+1)/2 2(3x-1)<5(x+1) 6x-2<5x+1 x<3

4x 5x-4x>-6 x>-6

15-9x<10-4x -5x<-5 x>1

4 x-3x+6≥4 -2x≥-2 x≤1

1 3+2x>x-1 x>-1-1 3 x>-(4 3) is exhausted.

1.(1/2 a-b)^2

x -4xy +4y ^2)

3.(a^2-b^2)^2

4.(2x+1)(x-2)

5.(x+2)(x-4)=0

x = -2 or x = 4

4（x-1/2）^2=16

x-1/2）^2=4

x = 5 2 or x = -3 2

4x-7)(x+2)=0

x = 7 4 or x = -2

So there is no solution. 0x<1/2

4-2x>=-2

x<=1

3/5 x-14x

x>-6

15-9x<10-4x

x>1, so x>1

4-2x>=-2

x<=1

1/3+2x>x-1

x>-4/3

So -4 3

{2＜3x-5①

3x-5≥4②

x>1 is obtained by

By x 3

x 3 (the same as the largest).

1. There are x cars 8x=4x+20 x=5 2, set the price of the field to x x answer: the ridge will never lose money 3, set the percentage x x= x-1= the last x+m+2=2x-3m+7 - x=-4m+5 x=4m-5 4m-5,<0 m<4 5 x+m+2>0 2x+2m+4>0 2x-3m+7>0 5m-4>0 m>5 4 4 5>m>5 4 m=1 I hope it will help you—-—