Junior high school math problem 40 points 2

Steps: 1, Let (let the unknowns) 2, Column (Column Equation) 3, Solution (Solve the equation) 4, Test (test result) 5, A.

Solution: -x-5x=1-3

6x=-2x=1/3

Solution: 1 2x-1 3x=1+1

1/6x=2

x=12 3, correct. This is because whether it is a number or an unknown number shift (i.e., moving from the left to the right or from the right to the left) has to be changed.

Definitely right. Believe me!

1. Solution: Set up ......(Write Unit).

2. Column. 3. Formation of the simplest form (ax=b).

4. Calculate x (do not write units).

5. Answer......Two.

1.Solution: 3-1=5x+x

6x=2 x=1/3

2.Solution: (1 2-1 3) x = 2

1/6x=2

x=12 three.

Correct with unknown numbers on one side, without the other side, move the item to change the number.

1.Solution: Set ......According to the title.

Column equation ......A......6x=2 x=1/3

1/2x-1=1/3x+1

1/6x=2

x=12 3.The correct equation shift term is to change the sign.

1.Solution: Set ......According to the title.

Column equation ......6x=2 x=1/3

1/2x-1=1/3x+1

1/6x=2

x=12

26 First Question.

First of all, the OAB triangle is equilateral, so the length of the three sides of OA, OB, and AB is 2.

The question is to ask about the area of the triangle opq in relation to time t.

Point Q is 1 unit per second moving from O to C, while P is 3 units per second from A to O and then to B.

Let's take a look at point P, when it moves to point O, the area OPQ is only related to the triangle of AOC, but after point O, it is more complicated, so let's consider the relationship between point P and point O:

When does point P move from point A to point O?

Remember that ABO is an equilateral triangle, so the length of AO is 2, so the distance from point A to point O is also 2.

The topic also said that p moves 3 units per second, so at 2 3 seconds, point p has already moved from point A to point O.

So the first case is 0 t 2 3 (from point A to point O).

Now let's look at point Q, how much time does it take for point Q to move from point O to point C?

To know this answer, we first need to calculate the distance of the OC.

OCA is known to be an isosceles triangle, i.e., OC AC, and angle C is equal to 120.

According to the theory of isosceles triangles, the angle o is equal to the angle a, and according to the theory of triangle sum 180, the angle o and the angle a are both 30 degrees.

And then we cut the triangle in half at angle c, so we have two triangles of 30 degrees, 60 degrees, 90 degrees. (120 divided by 2 60).

Since OA 2, the cut half is 1, which is the side of 30 degrees and 90 degrees.

According to the triangle of 30 degrees, 60 degrees and 90 degrees, the side of oc is 2 square 3, and after simplification, 2 square 3 3

In other words, it takes 2 to 3 3 seconds for Q to move from O to C.

So the second case is 2 3 (after case 1) t 2 open 3 3

In case 3, it is natural that Q goes from O to C, and P reaches point B.

The distance from A to O to B at point P is 4, and it moves 3 units per second, so the total time required is 4 3 seconds, so case 3 is 2 square 3 3 t 4 3 (you didn't write the answer, and I don't know if you need to count this).

26。(1) oc=2 3 3, so the motion time of q is 2 3 3, and the motion time of p is 4 3>2 3 3, because q stops, p also stops, so t<=2 3 3When p passes the o point, the height and bottom of the triangle change, and at this time t = 2 3.

2) D is on the edge of a triangle, when D is on OA, there are two cases, one is OD=OC=2 3 3, so D(2 3 3,0), the other is OD=DC, the height on the OC side, the right triangle with a 30 degree angle, OD=2 3, D(2 3,0), when D is on OB, only OC=OD, through D as the perpendicular line of the X axis, and also use the right triangle with a 30 degree angle, D(3 3,1), when D is on AB, it is a bit troublesome, as the perpendicular line of OC, The intersection with ab is d, which I don't really want to ask for, and I forget many formulas. See for yourself.

1.If it's equal to zero, it shouldn't be the same symbol.

There are two possibilities: 5-4a>0, 1-2a>0 a<4 5, a<1 25-4a<0, 1-2a<0 a>4 5, a>1 2 can be combined to obtain a>4 5 or a<1 2

The solutions are x=5, y=2 and x=2, y=7

x+y-p=0

So p=x+y=7 or 9

p = 7 or p = 9.

The first question is considered in 3 cases: 5-4a and 1-2a are greater than zero at the same time, less than zero, equal to zero, and the answer is less than half or more than five-quarters.

Question 2 p is equal to 9

14 Questions: 1, 15 Questions: 2, 16 Questions: Too lazy to count, 17 Questions: 18 Questions

Question 19:

Solution : Because if it is an integer, la-bl+lc-al=1

So a-b=0 ic-ai=1 or ia-bi=1 c-a=0 (which can be obtained from the non-negativity of the absolute value).

1. When a-b=0 ic-ai=1.

l a-b l+l b-c l+l c-a l

2. When ia-bi=1 c-a=0

l a-b l+l b-c l+l c-a l

2,8,tjyxz report.

How does c-a=o or 1 come from?

Report Andytouto

Because a, b, and c are all integers, a-b, c-a are all integers, and because la-bl and lc-al are positive integers and add up to 1, one is 0 and the other is 1

tjyxz report.

I'm sorry, I asked the wrong question, I want to ask how b-c=1 comes from a-b=0, c-a=1, the two formulas are added to get c-b=1, l b-c l=1 a-b=0, c-a=-1, the two formulas are added to get c-b=-1, l b-c l=1 a-b=1 c-a=0, the two formulas are added to get c-b=1, l b-c l=1 a-b=-1 c-a=0, the two formulas are added to get c-b=-1, l b-c l=1, I say equal to 2

Because |a-b|+|c-a|=1, the absolute values are all greater than or equal to 0, so a-b is greater than 0, c-a is greater than 0, so a is greater than b, c is greater than a, so c is greater than a is greater than b

I think it is the above, so the first formula on the question is equal to a-b+c-a=1, so c-b=1

The second formula is reduced to c-a+a-b+c-b, simplification is equal to 2c-2b, and two is extracted, so it is equal to 2 multiplied by 1, and the value is 2

Hope. 2, a, b, c are integers, and la-bl+lc-al=1, there is la-bl=1 and lc-al=0 or la-bl=0 and lc-al=1, c=a, or a=b, if c=a, there is lc-al+la-bl+l b-cl=2|a-b|=2, if a=b, there is lc-al+la-bl+l b-cl=2|c-a|=2, in summary, the value of LC-AL+LA-BL+L B-Cl is 2, 1, junior high school math problems, 30 points will be added afterwards.

Let a, b, and c be integers, and la-bl+lc-al=1, and find the values of lc-al+la-bl+l b-cl.