If a = 4x2-4xy + Y2, B = 23x2-43xy-y2. Find the value of a-3b

If a = 4x2-4xy + Y2, B = 23x2-43xy-y2. Find the value of a-3b

∵A=4x2-4xy+y2，B=23x2-43xy-y2，∴A-3B=（4x2-4xy+y2）-3（23x2-43xy-y2）=4x2-4xy+y2-2x2+4xy+3y2=2x2+4y2．

If the square of 4x + the square of y = 4xy, then 2x + Y / X-Y=

If the square of 4x + the square of y = 4xy,
（2x-y）²=0;
2x-y=0;
y=2x;
Then 2x + Y / X-Y
=(2x+2x)/(x-2x)
=-4;
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Let f (x) = the square of X - 2x + 3. X belong to the closed interval 0 to 3, then what is the range of the function

f(x) =x^2-2x+3
=(x-1)^2+2
minf(x) = f1) =2
f(0)=3
f(3)=9-6+3=6
Range = [2,6]

Boys in class 52 are 2 less than 60% of the class, and girls account for 44% of the class. How many students are there in class 52,

If there are X students in the class, then
44%X+(60%X-2)=X
4%X=2
X=50
Then the class number is 50

(2.4 + 3.6) times () equals () times 0.5 + 3.6 times
(2.4 + 3.6) times () equals () times 0.5 + 3.6 times 0.5

It's so simple. 0.5.2.4 uses the law of multiplicative distribution

Sequence 1 1 6 5 20 27

2^0+0=1
2^1-1=1
2^2+2=6
2^3-3=5
2^4+4=20
2^5-5=27
2^6+6=70
The nth term is [2 ^ (n-1)] + [(- 1) ^ (n-1)] (n-1)

Equation solution: there are 59 pieces of RMB 10 yuan and 5 yuan, a total of 470 yuan. How many pieces of RMB 10 yuan? How many pieces of RMB 5 yuan?

Let 10 yuan be x; 5 yuan be y
According to the following equation:
10X+5Y=470
X+Y=59
The solution is: x = 35, y = 24

What's the place? Find the rule and fill in 25.46.81--16.36

64

How many primes are there within 100? How many are there in total?

There are 25 prime numbers, 74 composite numbers, and 1, which are neither prime numbers nor composite numbers

Indefinite integral of 1 / (Sin & # 179; X + cos & # 179; x)
Such as the title

Generally, we don't use the universal formula until we have to,
This paper provides the method of non universal formula, and has some technical experience
The following are the specific steps to solve the problem: