Given ABCD = 1, find the value of 1 / (ABC + AB + A + 1) + 1 / (BCD + BC + B + 1) + 1 / (CDA + CD + C + 1) + 1 / (DAB + Da + D + 1)

Given ABCD = 1, find the value of 1 / (ABC + AB + A + 1) + 1 / (BCD + BC + B + 1) + 1 / (CDA + CD + C + 1) + 1 / (DAB + Da + D + 1)

abcd=1
abc+ab+a+1=abc+ab+a+abcd=a(bc+b+1+bcd)=a(bc+b+abcd+bcd)=ab(c+1+acd+cd)=abc(1+abd+ad+d)
Let x = ABC + AB + A + 1;
So the original formula = 1 / x + A / x + AB / x + ABC / x = (1 + A + AB + ABC) / x = 1;
Hope to adopt

When the 28th Olympic Games is the subject, does the predicate use the singular or the plural?

Odd number
The 28th Olympic Games is a competition, so it's singular

In △ ABC, ab = AC = root 5, BC = 4, find s △ ABC and tanb

Triangle height = (5-2 ^ 2) root = 1
Area s = 1 / 2 * 4 * 1 = 2
tanB=1/2

English translation
Go to a party of friends
Because my friends and I haven't seen each other for a long time, I'm looking forward to this gathering
3 visit Kim's home
What color hat does 4 Kim wear
In this way, the Party of a happy friend is over
I think we should cherish our friendship

Go to a party of friends
join a friend's party
Because my friends and I haven't seen each other for a long time, I'm looking forward to this gathering
Because of my friends and I have not met a long time,I am looking forward to this party of friends.
3 visit Kim's home
visit Kim's home
What color is Kim wearing?
What is the color of Kim's cap?
In this way, the Party of a happy friend is over
In this way,a happy gathering of friends in the end.
I think we should cherish our friendship
I think we should cherish our friendship.

In △ ABC, it is known that C = 120 ° and both sides a and B are two of the equations x2-3x + 2 = 0, then side C is equal to ()
A. 5B. 7C. 11D. 13

∵ A and B are two of the equations x2-3x + 2 = 0, ∵ a + B = 3, and ab = 2. Thus, in A2 + B2 = (a + b) 2-2ab = 5 ∵ △ ABC, C = 120 ° is known, ∵ C2 = A2 + b2-2abcosc = 5-2 × 2 × (- 12) = 7, and C = 7 is obtained

On the usage of the English phrase turn out
What do you mean by "sth turn out to be sth turn out + adj sth turn out sth"

It turns out to be a successful party Become Everything will turn out ...

Add 1 / 9 to a natural number, subtract the natural number from the denominator, and the fraction becomes 2 / 3. Find the natural number

(1+x):(9-x)=2:3
2(9-x)=3(1+x)
18-2x=3=3x
5x=15
x=3
The natural number is three

Is the adjective superlative always preceded by the? Is the noun after the adjective superlative always singular?
What if the superlative adjective is followed by an uncountable noun?
By the way Best wishes for you?

Is the superlative adjective always preceded by the whenever?
A: not necessarily. For example, the most advanced of many
Most of the students are in the playground
Don't use the
Is it necessary to use singular number when adding noun after the superlative adjective?
A: (see the answer to the above question)

Let f (x) = LG (1-x ^ 2) set a = {x | y = f (x)}, B = {y | y = f (x)}, then Cu (a ∩ b)=

A set represents the domain of a function
1 - x² ＞ 0
So - 1 < x < 1
The domain is (- 1,1)
B sets represent the range of functions
X & # 178; the minimum can be 0
So the range is (negative infinity, 0)
So a ∩ B = (- 1,0)
So Cu (a ∩ b) = (negative infinity, - 1] ∪ [0, positive infinity)

On phrases and phrases in English
What is a phrase? What is a phrase? For example
Are the following two phrases or phrases?
be ready for
each other

A: There is a big difference in English grammar
Citation 1: a group of words (mostly composed of more than two words) whose function is similar to a word can be called phrases. Phrases that act as nouns are called noun phrases; phrases that act as adjectives are called adjective phrases; phrases that act as adverbs are called adverb phrases; and so on
The king of Terror (noun phrase) will come one or later
Comparison: death (noun) will come one or later
He is a man of health
He is a healthy (adjective) man
He speaks English with fluency
= he speaks English fluent
Citation 2: phrases are like phrases, but they don't express parts of speech, such as it would, see, such as as ,in order that ．
Both noun phrases and noun clauses act as nouns and can be called noun equivalents. Similarly, adjective phrases and adjective clauses can also be called adjective equivalents, and adverb phrases and adverb clauses can be called adverb equivalents
Citation 3: a phrase is a larger unit than a word. A clause is a larger unit than a phrase. A phrase is a larger unit than a word. A clause is a larger unit than a phrase
Some phrases, such as a number of, lots of, a great deal of, have the same function as a single adjective
In of students, a number of modifies the noun (subject word) students, meaning close to some. If number is regarded as the subject word and of students as the attributive mechanically, it will be misunderstood
B. Zhang Daozhen's Concise English grammar is not
Words, phrases and clauses
There are several ways to express the elements of a sentence
1. Words:
They built a house
Barking dogs seldom bite
2. Phrases - a group of two or more words:
She doesn't know Chinese
We watch TV after supper
I've come to learn from you
3. Clauses - a short sentence similar to the sentence structure:
I'll come over to see you when I have time .
I'll come to see you when I'm free. Phrases are bigger than words. Clauses are bigger than phrases
She says she isn t coming back today .