If you are asked a few math problems, be sure to write out the analysis process

Solution:1Let the distance from point d to ab be de

AD deuces BAC to D

cad=∠dae

d perpendicular ab, and c=90°

dea=90°

c=∠dea

In ACD and ADE.

cad=∠dae

c=∠dea

ad=ad△acd=△ade(aas)

cd=de=7cm (the corresponding angles of congruent triangles are equal).

Ladies who are in class when answering the questions, I'm afraid you haven't studied in junior high school yourself! This question does not need to be proved by congruence at all! You just need to read what someone who doesn't need a full certificate to write it! Besides, their reasons are not complete, it's up to you!

It's too simple, I've never seen such a simple problem and the score is so high, this junior high school student doesn't seem to study well, so it doesn't solve the fundamental problem.

8.According to the right angle edge = the general of the hypotenuse.

Angle a = 30 degrees The answer is here, keep the team.

Don't ask all questions online, learn to think for yourself.

Study hard and make progress every day.

It can always be solved with vectors.

Hey, I can't even count ......

I'm so embarrassed, man, you didn't go to junior high school.

It's so simple, I don't even have the consciousness to do it!

Why do people keep asking these questions? Is it really that hard?

Do you do this every time?

I only know the result, and not pretending to be smart will prove that the front is closed.

1) Convergence at p>1;

2) divergence at p<1;

3) When p=1, the basic answer converges when Q>1 converges, and diverges when Q<1.

q=1, r>1 converges;

r 1.

I think the sentence at the end of this question seems to be foolish, if (at least 2 out of any 3 people in their hooded things belong to the same interest group), then at least 9*(2 3)=6, so the answer to the Qin Hall case should be 6

The number of people who can skate and swim (I don't know if they can play badminton): 98 + 90-165 = 23 people.

The number of people who don't know how to play badminton is (I don't know if there will be other two): 165-147 = 18 people.

Then there will be at least three kinds of people (the number of people who can do two things minus those who can't badminton): 23-18 = 5 people.

Skating, swimming: 98+90-165=23

All three: 23+147-165=5

It's junior high school... Fear of harming the plate.

Now that the rest of the LZ has been taken care of, I'll talk about 16 questions

If you haven't seen a similar method, this question is really difficult.

Let a satisfy the inner f(b) = f(a) + (b-a)[f'(a)+f'(b)]/2-a(b-a)³/12.(Put the original equation to accommodate f.)'''( ) is replaced by a).

As long as it is proved that there is (a,b) such that f'''( )=a.

Note f(x) = -f(x) + f(a) + (x-a) [f'(a)+f'(x)]/2-a(x-a)³/12.(This helper function seems complicated, but it actually subtracts the original equation left and right, and then replaces b with x).

Direct calculations yield:

f'(x)=[f'(a)-f'(x)]/2+f''(x)(x-a)/2+a(x-a)² /4.

f''(x)=(x-a)(f'''(x)-a)/2.

Obviously f(a)=f'(a)=0, f(b)=0

f(a)=0=f(b), from the rolle theorem we know that there is c (a,b) such that f'(c)=0.

f'(a)=0=f'(c), from the rolle theorem we know that there is (a,c) such that f''(ξ)=0.

a, hence f''(ξ)=0 => f'''(ξ)=a.

Surprisingly, there is a certain generality in this method! There is a class of problems with the median value theorem that can be solved using this method.

These problems are all in the mathematical analysis problem set, indefinite integrals are mainly commutations, the first two can be matched with a cosx or something, the last two problems are typical taylor, and then the inequality is simply estimated.

It's better to write it yourself.,Always write a few questions.,If you can't write, you can ask the teacher.。

If you go to Xinhua to buy, 1800 10 90% = 16200 yuan to buy at Walmart Because it is to buy 8 get one free, it is 80 yuan to buy 9, 1800 9 = 200, only 200 copies are enough, so it is 80 200 = 16000 yuan,

If you buy in Xinhua: 1800*10*yuan.

If you buy at Walmart: Buy x pcs, get x x 8 free. x+x 8=1800, x=1600. 1600*10=16000 yuan.

So, it's a good deal to buy at Walmart.

Xinhuadu: 1800*10*yuan.

Walmart buy eight get one free, that is, 8 * 10 = 80 yuan can buy 9 copies, so (1800 9) * 80 = 16000 yuan.

So it's a good deal to go to Walmart!

Xinhua: Yuan.

Wal-Mart: [1800 (8+1)] x8x10=16000 yuan.

Wal-Mart is advantageous.

If you buy it in Xinhua, then: total **=1800 10 yuan) If you buy it at Walmart, then: you want to buy x copies. There is x+x 8=1800 to get x=1600 (parts).

So total**=1600 10=16000 (yuan), so in general, it will be cheaper to buy at Walmart.

I don't know if I'm satisfied!

Of course it's a good deal for Wal-Mart.

Xinhuadu fee: 10*1800*

Walmart fee: 10 * 1600 (buy 8 get 1 free, get 200 free copies, 1800 copies) = 16000

7:30 a.m. to 5:30 p.m

10 hours in total.

Rest for 2 hours.

So work for 8 hours.

I made 48 pieces.

48 divided by 8 = 6

I do 6 pieces per hour for adoption.

5:30 p.m. is 17:30, so Xiao Li works a total of 17:30-7:30 = 10 hours.

Take a two-hour break, so there are 10-2=8 hours left.

So the speed is 48 8 = 6 pieces per hour.

Hello! Solution: Let A and B produce x and y parts per hour, according to the topic

8x+6y=312

5y=2x solution gives x=30

y=12, so the number of parts produced by A and B is.

8x=8*30=240 (pcs).

6y=6*12=72 (pcs).

A: A and B produce 240 and 72 parts respectively.

B's 5 hours of work is equal to A's 2 hours of work, and B's 1 hour of work is equal to A's 2 5 = hours).

Now, B has produced 6 hours, which is equivalent to A has produced: *6= (hours), A has produced 312 (8+) in one hour

A 8 hours produced: 30 * 8 = 240 (pcs) B 6 hours produced: 312 -240 = 72 (pcs).