If the function y = f (x) is a decreasing function on (- ∞, 0), and f (x) is an even function, then the relationship between F (- 3) and f (2.5) is () A. F (- 3) > F (2.5) B. f (- 3) < f (2.5) C. f (- 3) = f (2.5) d

If the function y = f (x) is a decreasing function on (- ∞, 0), and f (x) is an even function, then the relationship between F (- 3) and f (2.5) is () A. F (- 3) > F (2.5) B. f (- 3) < f (2.5) C. f (- 3) = f (2.5) d

∵ function y = f (x) is a decreasing function on (- ∞, 0) ∵ f (- 3) > F (- 2.5) ∵ f (x) is an even function ∵ f (2.5) = f (- 2.5) ∵ f (- 3) > 2.5), so a is selected

It is known that: F (x + y) + F (X-Y) = 2F (x) * f (y), x.y takes any real number and f (0) is not equal to 0. It is proved that f (x) is an even function

F (0 + 0) + F (0-0) = 2F (0) * f (0)
And f (0) is not equal to 0
So f (0) = 1
When x = 0 and Y is any real number
f(0+y)+f(0-y)=2f(0)*f(y)=2f(y)
So f (- y) = f (y)
So f (x) is even function

Let ABCD = 1, find the value of "AB / 1 + A + AB + ABC" + "BC / 1 + B C + BCD" + "CD / 1 + C + CD + CDA" + "DA / 1 + D + Da + DAB"

ab/(1+a+ab+abc)=1/(1/ab+1/b+1+c)=1/(cd+acd+1+c)=1/(1+c+cd+cda)
bc/(1+b+bc+bcd)=c/(1/b+1+c+cd)=c/(cda+1+c+cd)=c/(1+c+cd+cda)
da/(1+d+da+dab)=cda/(c+cd+cda+dabc)=cda/(1+c+cd+cda)
Therefore, the original formula = (1 + C + CD + CDA) / (1 + C + CD + CDA) = 1

Is the predicate singular or plural when the Olympic Games is the subject

The predicate is the singular form of the third person
reason:
You can think of it as a whole, but the reasonable explanation is that the three words you typed form a proper noun, just like the Great Wall. Since it is a proper noun, of course the predicate verb should use the third person singular form

In △ ABC, AC = 5, BC = 2, and tanb = 1, find the length of ab
Such as the title

Tanb = 1, B = 45 ° or B = 135 ° CoSb = (AB ^ 2 + BC ^ 2-ac ^ 2) / 2Ab * BC, CoSb = √ 2 / 2 or CoSb = - √ 2 / 2, AB ^ 2 + BC ^ 2-ac ^ 2 = √ 2Ab * BC, AB ^ 2 + 4-25 = 2 √ 2Ab, AB ^ 2-2 √ 2Ab + 2 = 23 (ab - √ 2) ^ 2 = 23, ab = √ 23 + √ 2 (negative value discarded)

English translation
Social turbulence, facing foreign aggression, weakening national strength, ideological education, spiritual civilization, environmental protection, facilities planning and construction, Green Olympics, science and technology Olympics, people's Olympics

Social unstability,faced with foreign aggression,weakened national strength,ideological education,spiritual civilization,environmental work,facilities planning and construction,Green Olympics,Hi-tech Olympics,Human's Olympics

The solution of the equation x + 1 / x = C + 1 / C (C is a constant not equal to 0) is C or 1 / C. find the solution of the equation x + 1 / (4x-6) = (a ^ 2 + 3A + 1) / 2A (a is a constant not equal to 0)
Do me a favor, er

x+1/(4x-6)=(a^2+3a+1)/2a -->x+1/(4x-6)=a/2+3/2+1/(2a)
The two sides multiplied by 2 are as follows:
2x+1/(2x-3)=a+3+1/a
2x-3+1/(2x-3)=a+1/a
Therefore:
2x-3 = a or 2x-3 = 1 / A
X = (a + 3) / 2 or x = 1 / (2a) + 3 / 2

The explanation and sentence making of English phrases with different synonyms
Here are some phrases with similar meaning but different usage
When explaining, please indicate whether the phrase is used to modify countable or uncountable nouns
Make one sentence for each phrase, not one sentence for all phrases!
a good deal
a good deal of
a good many
a great deal
a great deal of
a great many
a little
a lot
a lot of
a matter of
a number of
a series of
a variety of
Note the modification of "countable" or "uncountable" noun!
And sentence, sentence is not too long, can be used to the word
Sentence translation.
The nouns at the end of some sentences do not indicate that they are countable or uncountable.

Have a good deal friends.
A good deal of housework can be mechanized.
I read a good many English books.
He suffered a great deal at the end of his life.
You can save a great deal of time and effort when you know where to look.
A great many parks lost trees in the hurricane.
If you are a little flying bird.
You must get a lot from them.
A lot of trouble is caused by racism.
It is not a matter of forgiveness.
As a writer,you must include a number of things in your story.
Life is a series of tests.
Raindrops come in a variety of sizes,even within the same storm.
We can judge the countable noun or uncountable noun by adding s to the noun after each phrase

If three consecutive natural numbers are multiples of 17, 19 and 21, then the smallest of the three consecutive natural numbers is the smallest______ ．

The least common multiple of 17, 19 and 21 is 17 × 19 × 21 = 6783 (6783 + 17) × 2 = 3400 (6783 + 19) × 2 = 3401 (6783 + 21) × 2 = 3402, so the answer is: 3400

Multiple adjectives modify the order of a noun

1、 The order of English adjectives: the order in which two or more adjectives modify the same noun is explained in general grammar books. For example, in Langwen English grammar, it is described as: quality → size → old and new → style → color → place of origin → past participle