Ask the math master to help solve it, and urgently ask the math master to solve the math problem

One. Fill in the blank 1If a square is enlarged by 2:1, its area will be expanded by a factor of (4).

2.The ratio of A and B is 4:5, B is A's (times, A is B's (80)%.

Two. True or False:

and 60:4 can make up the ratio. (Right).

2.If y = 8/x, then x and y are inversely proportional. (Right).

3.The scale bar is fixed, and the distance on the graph is proportional to the actual distance. (Right).

4.The radius of the circle is proportional to its diameter. (Right).

18 = 2/3 is also a ratio. (False).

6.The base of the parallelogram is fixed, and the area of the parallelogram is proportional to the height. (Right).

Three. Multiple Choice:

1.The surface area of the square is proportional to (b). a.Ridge length bThe area of each polygon cVolume.

2.Shrinking a flat figure by 1:10 means that (a) becomes the length b. of each side of the original 10th figureThe area of the shape.

3.The total number of trees in the index is certain, the survival rate of the book and the surviving trees (a). a.Proportional binversely proportional cDisproportionate.

4.The area of the triangle is fixed, the base and the height (b). a.Proportional binversely proportional cDisproportionate.

Four. Application:

1.A car travels 60 kilometers per hour from A to B and can be reached in 3 hours. When returning, if the speed is increased by 20%, how many hours can I get back to A? (Proportional solution).

Solution: Set x hours to return to place A.

60*3=60*(1+20%) x

Solution: x=2The train traveled from station A to station B in 3 hours for 6/11 of the whole journey. At this rate, how many hours will it take for the train to reach the station? (Proportional solution).

6/11）/（1-6/11）=3/x

x = hours).

y=kx=b???Question it)!

1. First bring the two points A and B into Y to get K, B!

2. Let the coordinates of p be (x,y).

Then write the straight line where AP and PB are located! p(x,kx+b) is an isosceles triangle, and the length of ap and bp is calculated according to the equality of the two sides and between the two points, which is represented by x.

ap=bp=>p's coordinates!

3, the third question, alas, you can know how to do it by drawing by yourself (I'm a little irresponsible, but there are a lot of words to write, even if I write the steps, you don't necessarily understand)!

It's too unclear.

See for yourself.

Can not see clearly.

Take a clear picture.

Let x=y=z=1 3, obviously meet the conditions of the problem. Bring in the required expression to get 1+1+1=3. So choose C

Special Value Method. Ask for adoption!

From the given two equations, the expression that represents x and y is obtained by z, and then substituted into the equation found, and finally z will be eliminated to obtain 3

The original formula is =丨1 3-1 2丨+丨1 4-1 3丨+丨1 5-1 4丨+.丨1 2010-1 2019丨.

Because 1 2 1 3

So 丨1 3-1 2丨=1 2-1 3

In the same way丨1 4-1 3丨=1 3-1 4 add the two formulas to reduce one-third.

The same back put a quarter, a fifth, about off.

。Column yourself and finally get 1 2-1 2010 = 502 1005 Good luck.

Friend, you have to understand that because the result of 1 3 + (-1 2) = (1 3-1 2) is negative, it is |1/3-1/2|=-1 3-1 2)=1 2-1 3, everything else is the same. Solution:

The absolute value of one-third plus minus half is one-half minus one-third, and the absolute value of one-quarter plus minus one-third is one-third minus one-quarter, and so on, the minus one-third of the first term and the positive one-third of the second term are eliminated, and the subtracted value of each item and the positive value of the latter item are eliminated, and finally it is one-half minus one thousand and one-tenth.

That is, the absolute value of opening one-third plus minus one-half of the absolute value = 1 2-1 3 The next few terms are like this, so in the end, only the first two items remain, 1 2-1 2010

One-half minus one-third + one-third minus one-quarter + one-quarter minus one-fifth +. One thousand and nine minus one thousand and one tenth = one half minus one thousand and one tenth = one thousand and one thousand and four.

+.+ Rub, I read your question for a long time before I understood.