In the first year of junior high school, ordinary math problems are solved by masters

The opposite number is the relationship between positive and negative numbers, negative negative is positive, plus or minus is negative) should be equal to)

Both positive and negative numbers include decimals).

2，1，0，-1，-2，-3） a

5.Negative or 0

(-2,-1,0,1,2,3).

9.Since the absolute value is a non-negative number, both are 0 a=1, b=2, a+b=3, b=-5

12.No.

Or a negative number.

Piece. When b = -5 A = -1, b = -5

12.No.

b, c, a, c, a, 0 or negative ,0 1,<7 ,a+b=3 ,a=1,b=-5 ,5<-4<-3<3<4<5 ,not ,1

That's how I hope it helps!

Assuming that a large meadow is divided into 6 patches by area, the small patches of grassland are 3 patches.

From the inscription, it can be seen that 4 pieces of large grass were hoeed in the morning, 2 pieces were hoeed in the afternoon, and 2 pieces of small grass were hoeed in the afternoon, that is, 8 pieces were hoeed that day.

The rest of that. One piece per day.

The hoe is over. From this, it can be seen that there were 8 workers hoeing grass that day, that is, there were 8 workers on the farm, since the brother downstairs has doubts, I will say it another way:

Set a small grassland area of a, then a large grassland area is 2a, and set the total number of workers for x, according to the meaning of the topic: the average area of each worker hoeing grass per day is (calculated by large and small grasslands respectively) 1, large grass area 2a

Divide by [half a day (morning) for all workers + half a day (afternoon) for half of workers] i.e. 2a (

2a This is also the area of the small piece of grass that is left for the day.

2. A small piece of grass A minus the remaining small pieces of the day and divide it.

Half of the workers have half a day (afternoon).

a-2a/(=2a/

Through the above equation, x=8 is obtained

There are x people on the farm, and the amount of weeding per person per day is y

Then the amount of weeding in a large area of grassland at noon is, the amount of weeding in a large area of grassland in the afternoon is the amount of weeding in a small area of grass in the afternoon, and the next day a person just removes the remaining piece of small land is 1y, and because the area of a large area is twice that of a small piece of land.

So divide both sides by y at the same time to get x 8

Suppose there are x workers, and the large meadow has the area of 2a plots and the small meadow has the area of a. According to the problem, a worker can hoe a piece of land in a day, and the equations x+x 2=2a and x 2+1=a are solved so that x is 4

There are x people, and the amount of weeding is y

Divide by y on both sides at the same time.

Assuming that the time between the athlete leaving the team and rejoining the team is t hours, then 35t + 45 (t-10 45) = 10

80t-10=10

t = the time between the time the athlete leaves the team and the time he rejoins the team is the hour (15 minutes).

From the beginning to the final meeting, the 35km h athlete and the 45km h athlete walked a total of 20km without stopping in the process, so, the time t=20 (35+45)=

The time used by an athlete is 10 45 = 2 9 (hours) and the athlete walks back x hours, then.

x+2/9）*35+45*x=10

x=1 36 (hours).

The shared time is: (2 9) + (1 36) = 9 36 = 1 4 (hours).

Draw a schematic diagram of the itinerary and find that the total distance between the average athlete and the transcendent is 20 kilometers, so let x hours meet, the equation is 35x+45x=10*2, and the solution is x=hours.

1.If |x+1|+ root number y-6 = 0Find the value of x+y.

Remember to use it directly later.

x+1|+√y-6)=0

If the sum of several non-negative numbers is 0, then these numbers are 0

i.e. x+1=0

y-6=0 then x+y=5

2.Use 200 squares of the same size to transfer a living room with an area of 50 square meters, and choose the floor tiles with a side length that is the most economical material.

Solution: Let the edge length be x

then 200x = 50m (the total area of 200 floor tiles is 50m).

Then x=A: The floor tiles with side lengths should be selected to save the most material.

3.If the number A satisfies the condition|2008-a|+ root number a-2009=a to find the value of a-20082.

Solution: |2008-a|+√a-2009)=a

A-2009).

then A-2009 0

i.e. a 2009

So the original formula is (absolute value open).

a-2008+√(a-2009)=a

a-2009)=2008

a-2009=2008²

i.e. a-2008 =2009

Your title 20082 should be 2008).

4.Observe all sorts. What to find. Can you express your findings in a general formula?

Root number 11-2 = 3

Root number 1111-22 = 33

Root number 111111-222 = 333

Solution: It's very simple.

an=√[(1+10+10²+.10^n)-(2+2x10+2x10²+2x10^(n-1)]

10 n is to the nth power of 10.

10 (n-1) means 10 to the n-1 power.

]"The formula inside is all under the root number.

I'm sorry, I'll only ask the first question.

1. x=-1， y=6

Because the absolute value must be a non-negative number, and the root number must also be a non-negative number, so if the sum of the two equals 0, only two of them are equal to zero.

Solution: Set the discount to x

x A: The minimum discount is based on the original price**.

Set the purchase price to $10. The volume of goods is m

When half is sold, the profit is 5m2=

Total profit target: 3m

Profit 3m-2,5m=

Let the rest of the pricing be x:

x-10)×m/2≧

x-10≧1x≧11

A: The remaining fruits can be discounted according to the original price**.

Let the cost be x, then the initial pricing is, and I hope that the average ** of all the final will not be less than, so the following **y, y*1 2+>=, so y*1 2>=, so y =, so the lowest price is, the initial pricing is, so the discount is, so the discount.

Question 1: -3 power of (1 2) = 8, 0 power = 1 of 2008, 2 power of (-3) = 9, sin60 = (root number 3) 2, the result is added by yourself.

This is obviously a topic for the third year of junior high school, so there is no hurry.

+1+ to the third power

Root number root number 3) + root number 12 4

2 root number 3 root number 3 3 + root number 12 4

Root number 12 4 - root number 3

Root number 3|+ root number.

3-2 + root number 3 + root number.

Root number 3 + root number 2

1.Original = 2*3+1+9 - root number 3 2 = 18 - root number 3 22Original = (2 x (root number 3+1)) (root number 3-1) (root number 3+1) - root number 3 2 - root number 3 + root number 3 2

Root number 3 + 1 - root number 3 2 - root number 3 + root number 3 2 = 13Original = 3 - 2 - root number 3) + 1 = 2 + root number 3

Is this the first day of junior high school?

The bar ...... the first year of high school

1) Because the EOC is 70 degrees, OA bisects the EOC, so AOC is 35 degrees, and because AB and Cd intersect at the point O, the EOC is 35 degrees, and the top angle is equal.

2) Because eoc: eod=2:3, so eoc is equal to 180 degrees multiplied by two-fifths equals 72 degrees, and eod is equal to 180 degrees multiplied by three-fifths equals 108 degrees, because oa bisects the angle eoc

So AOC is equal to 36 degrees, and because AOC and BOD are opposite top angles, BOD is 36 degrees.

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