Mr. Wang wants to print an article. The number of lines and the number of words per line are shown in the following table: the number of words per line; 16 20 25 32 40 50 lines; 100 80 64 50 40 32 It can be seen from the above table that the number of words printed on each line is the same as the number of lines to be printed

Mr. Wang wants to print an article. The number of lines and the number of words per line are shown in the following table: the number of words per line; 16 20 25 32 40 50 lines; 100 80 64 50 40 32 It can be seen from the above table that the number of words printed on each line is the same as the number of lines to be printed

It can be seen from the above table that the number of lines changes with the number of words printed in each line. The number of words printed in each line increases, but the number of lines decreases. Moreover, the product of the number of words printed in each line and the number of lines to be printed is 1600

Mr. Wang has printed 40% of a manuscript, and the number of words printed is 500 words less than the rest. How many words are there in this manuscript?

1-40% = 60 '- 40% = 20p0 divided by 20% = 2500
Pure hand fight, choose me!

It is known that in RT △ ABC, ∠ C = 90 °, a + B = 14, C = 10, the area of △ ABC is ()
A. 48B. 24C. 96D. 20

∵ a + B = 14 ∵ (a + b) 2 = 196 ∵ 2Ab = 196 - (A2 + B2) = 96, ab = 48, ∵ 12ab = 12 × 48 = 24

It is known that m and N are nonempty proper subsets of set I, and m and N are not equal. If n ∩ (∁ IM) = ∞, then m ∪ n = ()
A. MB. NC. ID. ∅

By means of Wayne's drawing, we can draw a set which satisfies the problem that m and N are nonempty proper subsets of set I, and m and N are not equal, if n ∩ (∁ IM) = 0. From the graph we can get: m ∪ n = M. so we choose a

As shown in the figure, △ ABC is a steel frame, ab = AC, ad is the support connecting a and the midpoint D of BC

In △ abd and △ ACD, ≌ AB = acbd = CDAD = ad, ≌ abd ≌ ACD (SSS)

Given a (radical 3,0) and circle C: (x + radical 3) ^ 2 + y ^ 2 = 16, point m moves on circle C, moving point P is on radius cm, and | PM | = | PA |, the moving point P is fixed
Given that a (radical 3,0) and circle C: (x + radical 3) ^ 2 + y ^ 2 = 16, point m moves on circle C, moving point P is on radius cm, and | PM | = | PA |, the minimum distance from moving point P to fixed point B (- A, O) is obtained

Let the distance between P (x, y) and a (x-radical 3) ^ 2 + y ^ 2 and m be 4-radical (x + radical 3) ^ 2 + y ^ 2. These two are equal, so (x-radical 3) ^ 2 + y ^ 2 = 4-radical (x + radical 3) ^ 2 + y ^ 2. Then we can count them. Finally, we get x ^ 2 / 16 + y ^ 2 / 4 =

Finding indefinite integral ∫ x ^ 2 * e ^ xdx=

∫ x^2*e^xdx=
=∫x^2de^x
=x^2e^x-∫e^xdx^2
=x^2e^x-2∫xe^xdx
=x^2e^x-2∫xde^x
=x^2e^x-2xe^x+2∫e^xdx
=x^2e^x-2xe^x+2e^x+C

There is a sum of money, if it is used to buy 10 desks, if it is used to buy 40 desks and chairs, how many sets can I buy at most?

1 ÷ (1 / 10 + 1 / 40) = 8 sets

Proof of parallelogram rule
How to prove the rule of parallelogram by theory

The sum of squares of two hypotenuses is equal to the sum of squares of all sides. Let a parallelogram be ABCD
And certification:
AB^2+BC^2+CD^2+DA^2=AC^2+BD^2;
Because AC = AB + BC
BD = Ba + ad, which is the addition of vectors;
It can be obtained directly by vector operation

A shopping mall is going to buy a batch of two different types of clothes. It is known that it costs 1810 yuan to buy 9 pieces of A-type clothes and 10 pieces of B-type clothes. If it buys 12 pieces of A-type clothes and 8 pieces of B-type clothes, it costs 1880 yuan. It is known that one piece of A-type clothes can make a profit of 18 yuan, and one piece of B-type clothes can make a profit of 30 yuan. In order to make a profit of no less than 699 yuan in this sales, and A-type clothes can make a profit of 18 yuan (1) how much is the purchase price of model a and B? (2) If it is known that the purchase of model a clothes is more than 4 pieces more than twice that of model B clothes, the store can have several plans in this purchase, and the purchase plan is briefly described

(1) Suppose that each piece of clothing of type A is x yuan, and each piece of clothing of type B is y yuan, then 9x + 10Y = 181012x + 8y = 1880, and the solution is x = 90Y = 100. Answer: each piece of clothing of type A is 90 yuan, and each piece of clothing of type B is 100 yuan. (2) if M pieces of clothing of type B are purchased, then (2m + 4) pieces of clothing of type A are purchased, and the solution is 18 (2m + 4) + 30m ≥ 6992m + 4 ≤ 28, and the solution is 192 ≤ m ≤ 12, ∵ m is positive integer A: there are three purchase plans: (1) buy 10 pieces of B-type clothes and 24 pieces of A-type clothes; (2) buy 11 pieces of B-type clothes and 26 pieces of A-type clothes; (3) buy 12 pieces of B-type clothes and 28 pieces of A-type clothes