Junior 2 math problems: Solving problems of equations

List a binary equation.

Let A do x every day and B do y every day, assuming that the engineering quantity is 1, then there is:,24(x+y)=1,1-20x=40y, and solving the equation can get 30 days for A and 120 days for B.

In other words, since you want to list the solutions of the equations, then you must have more than binary to have the system of equations, and there is no unary system of equations, so there is no answer that can satisfy you.

1.Let the amount of work to be completed by A per day be x and B is y 24*(x+y)=20x+40y

So x=4y shows that A is dry for one day and B is dry for four days.

There is a second condition: if A alone 20 days, the rest of B will do, and it will take another 40 days to complete the whole project.

B does 40 days, A only needs 10 days, so A does it alone, it takes 30 days.

Take 120 days to do it alone.

In the maintenance project of a bridge, it is proposed to be carried out by A. B: Two engineering teams work together to complete a project. From the information of the two engineering teams, it can be known:

If the two engineering teams work together, 24 days will be the same time to complete the project; If the two engineering teams work together for 18 days, and the first engineering team works separately for another 10 days, the project will be completed. Seek A. The number of days required for two engineering teams to complete the project individually.

Set up two kinds of refrigerators to produce x and y units each this month.

x+y=1000

Solution x=350

y=650

Let the velocity of B be xkm h

Then the velocity of A is.

40/x=40/

x=16A: B's velocity is 16 km h, and A's velocity is 40 km h.

B is 16 km hour and A is 40 km hour.

A takes less than one and a half hours to arrive than B, so there is 40 V B B.

Solution v B = 16km h

v A = 40 km h

B's velocity x kilometers is A's velocity in kilometers.

40/x-40/

Solution x=16

Solution: Suppose that B is riding a bicycle at a speed of x kilometers per hour, and A is riding a motorcycle at a speed of kilometers per hour.

Because A and B travel the same distance, both of which are 40 kilometers, then the equation can be calculated according to "A arrives 1 hour earlier than B", and note that B has an hour ahead and should be counted.

40/x-40/

x = 16 kmh).

A: B is riding a bicycle at a speed of 16 km/h, and A is riding a motorbike at a speed of 40 km/h.

Let B's velocity be x hours and kilometers then according to the title:

40 / x = 40 / +

Additional Idea: The volume of two cylinders is equal, while the volume formula for a cylinder is.

Square of radius * Cylinder height (length).

According to the volume equality, you can column:

Solution, according to the meaning of the topic:

10 * 10 * 100 = * 5 * 5 * x solution. x = 400(cm)

A: The length of the billet is 400cm

Thank you

×（10）∧2×100=π×（5）∧2×x

Just find x.

ps: 2 is squared.

The two factories A and B can process x and y pieces of new products respectively 1200 x-1200 y=10 per day

y=x=40

y=60

Assuming that factories A and B can process x and y new products respectively every day, then the tool problem is a system of equations: 1200 x +10=1200 yx=

Solve the above equation to obtain: x=60, y=40

A: The two factories can process 60 and 40 pieces of new products per day.

Solution: Let the equation be completed in x days, so A does x days and B does x + 4 days 1 x + 1 (x+4) + (x-1) (x+4) = 1 and multiplies x(x+4) on both sides of the equation at the same time

x+4)+x+x(x-1)=x(x+4)x+4+x+x²-x=x²+4x

x²+x+4=x²+4x

x+4=4x

3x=4x=4/3

The stipulated date is 4-3 days.

Solution: Let the width of the rectangle be x cm, then the length is (x+40) cm, and the diagonal is x+x+40-80=(2x-40) cm, according to the Pythagorean theorem, there is the equation:

x²+(x+40)²=(2x-40)²

2x²+80x+1600=4x²-160x+16002x²-240x=0

x(x-120)=0

x1=120, x2=0 (not on topic, should be discarded) so x=120

A: The width of this rectangle is 120 cm.

Set the annual interest rate of Type A Bond x the annual interest rate Y of Type B Bond

y=x-2 (1)

1000xy=108 (2)

Let the annual interest rate of Type B bond be x.

1000x(x+2%)】xx+1000x(x+2%)=108 is to find out the interest obtained from the purchase of a type A bond for one year, and then multiply this interest by the annual interest rate of the type B bond, and the interest obtained is the interest of the type B bond, plus the principal (the interest earned by the type A bond), that is, 108 yuan. Trust me.

Finally, we use a quadratic function to get x=8%.

Steps: Solve first, in the design, don't talk about it. 1000 multiplied by [x's square] + 20x + 1000x + 20 = 108

x squared + [51 50] xx = 11 125

x+51 100) = 3481 open root.

x+51/100=59/100

The solution yields x=8 100, i.e. 8%.

I think it's very good, as long as you have a little bit of skills, follow my steps, and express it in mathematical language, it's absolutely right. If you don't understand, read it a few times. I finally answered it once, and I hope it can be adopted.

I'm sorry I suddenly remembered yesterday that I didn't add 2% and the final answer should be 10%.

Solution: Let Xiao Wang's self-driving speed be V, and the time taken is t

Then, the speed of taking the bus is 2V+9, and the time taken is 3T 718=VT (1)18=3T 7(2V+9) (2) from (1) (2) to obtain t=2 3

v=27, that is, Xiao Wang drove an average of 27 kilometers per hour by self-driving.

Solution: If the average hourly travel of self-driving cars is x kilometers, then the average hourly travel by bus is (2x+9) kilometers.

Establish equations based on the workshop used:

18 (2x+9) = 18 x multiplied by 3 7

Get x=27A: Xiao Wang drives an average of 27 kilometers per hour to work by self-driving.

When the distance is the same, time is inversely proportional to velocity. If you directly set up x kilometers per hour for self-driving, then the bus will be (2x+9) kilometers per hour.

x/（2x+9）=3/7

Solve x=27

Solution: Let Xiao Wang drive to work by self-driving on average, driving x kilometers per hour.

18/x*3/7*(2x+9)=18

If you don't understand, you can ask.

Suppose Xiao Wang drives an average of x kilometers per hour to work by self-driving 18 x*3 7=18 (2x+9)54 7x=18 (2x+9)54 (2x+9)=126x18x=486x=27 Xiao Wang travels an average of 27 kilometers per hour by self-driving to work.

Solution: Set the nickname speed x kilometers per hour, and the speed of Xiaojie is y kilometers per hour.

2 hours 40 minutes = 8 3 hours.

Xiao Ming walked the rest of the way, and the rest of the road was actually the road that Xiao Jie walked before the two people met, Xiao Jie walked, and the rest of the road was the road that Xiao Ming walked before they met).

by the title. From the above two formulas we get x=16 and y=12

Answer: The speed of the nickname is 16 kilometers per hour, and the speed of the nickname is 12 kilometers per hour.

Nervous, apprehensive.

Solution: Set the nickname speed x kilometers per hour, and the speed of Xiaojie is y kilometers per hour.

2 hours 40 minutes = 8 3 hours.

Xiao Ming walked the rest of the way, and the rest of the road was actually the road that Xiao Jie walked before the two people met, Xiao Jie walked, and the rest of the road was the road that Xiao Ming walked before they met).

by the title. From the above two formulas we get x=16 and y=12

Answer: The speed of the nickname is 16 kilometers per hour, and the speed of the nickname is 12 kilometers per hour. Oh no.

The time spent on the encounter is equal.

x=16,y=12

1. Let the speed of A be 3x km/h, and the speed of B be 4xkmh6 (3x)+20 60=10 (4x).

The solution is x=3 2

So the velocity of A is 3x=9 2=km/h.

B's velocity is 4x=6 km/h.

2. Set the driving speed of the first hour to x kilometers per hour.

x×1+（180/x-40/60-1）×

x+x=60

A: The previous hour's travel speed was 60 km/h.