How to read pear English

How to read pear English

Pear: [P3 & # 601;]

In the parallelogram ABCD, BC + DC + Ba = 1 is simplified___ ．

∵ in the parallelogram ABCD, DC and Ba are a pair of opposite vectors, ∵ DC = - BA, ∵ BC + DC + Ba = bc-ba + Ba = BC

Factorization x ^ 3-2x ^ 2 + 1

x^3-2x^2+1
=x³-x²-x²+1
=x²(x-1)-(x-1)(x+1)
=(x-1)(x²-x-1)
Or continue to decompose
x^3-2x^2+1
=x³-1-2x²+2
=(x-1)(x²+x+1)-2(x+1)(x-1)
=(x-1)[(x²+x+1)-2(x+1)]
=(x-1)(x²-x-1)
=(x-1)[x-(1＋√5)/2][x-(1-√5)/2]
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If n is a positive integer, we prove that n ∧ 5-5n & # 179; + 4N can be divided by 120

Proof: n ^ 5-5n & # 179; + 4N
=n(n^4-5n^2+4)
=n(n^2-1)(n^2-4)
=n(n-1)(n+1)(n-2)(n+2)
=(n-2)(n-1)n(n+1)(n+2)
Because n is a positive integer, when n is less than or equal to 2, the value of the formula is 0 and can be divided by 120
When n is greater than 2, the formula is the multiplication of five continuous natural numbers. Common sense shows that there are at least one multiple, one multiple of 2, one multiple of 3, one multiple of 4, and one multiple of 5 among the five continuous natural numbers, so that their score is at least a multiple of 120. Therefore, the equation can be divisible by 120

The two focal points of drag circle C: x ^ 2 / A ^ 2 + y ^ 2 / b ^ 2 = 1 (a > b > 0) are F1 and F2. Point P is on ellipse C, and Pf1 is vertical to F1F2,
The absolute value of Pf1 is 3 / 4, and the absolute value of PF2 is 14 / 3. (1) the equation of solving ellipse C. (2) the equation of solving line L is obtained when the line L passes through the center m of circle x ^ 2 + y ^ 2 + 4x-2y = 0, intersects ellipse C at two points a and B, and a and B are symmetrical about point M

a=(PF1+PF2)/2=(3/4+14/3)/2=65/24
F1F2 = root (PF2 * pf2-pf1 * Pf1) = root (196 / 9-9 / 16) = (root 3055) / 12
B = root (a * a-f1f2 * F1F2 / 4) = (root 1170) / 24
So write the elliptic equation for yourself! You must have copied the wrong number
(2) The center coordinates are (- 2,1)
Let the equation of l be y = K (x + 2) + 1
Substituting into the elliptic equation, a quadratic equation AX ^ 2 + BX + C = 0 is obtained
-B / a = X1 + x2 = - 2 * 2, that is, the X coordinate of the center of the circle is multiplied by 2, and then K can be obtained; (here, using the symmetry principle, M is the midpoint, and the midpoint coordinate is half of the sum of the coordinates of the two ends.)
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What are the two prime numbers in 2005

2003 and February
1、2003＋2＝2005；
2. 2 is the smallest prime number. There is no other common divisor except 1 and itself

Given the function y = ax + B (a, B are constants), when x = 1, y = 8, when x = 2, y = 15, find the square of a plus B to get the square

When x = 1, y = 8, when x = 2, y = 15
So 8 = a + B
15=2a+b
subtract
a=7,b=8-a=1
So a & sup2; + B & sup2; = 50

12. Given the function f (x) = b * a ^ x (where a and B are constants, and a > 0, a is not equal to 1), the image passes through a (1,6), B (3,24). (1) find f (x)

Column equations to solve OK, not too complex
a=2
b=3

2X + 5 of x equals 5 of 33

x/(2x+5)=33/5
33(2x+5)=5x
66x+165=5x
66x-5x=165
61x=165
x=165/61

Let X and y be independent of each other, and X ~ n (0.1), y ~ n (1,4). (1) find the probability density f (x, y) of two-dimensional random variables (x, y); (2)

Let X and y be independent of each other, and X ~ n (0,1), n (1,4). (1) find the probability density f (x, y) of two-dimensional random variable (x, y). (2) let the distribution function of (x, y) be f (x, y), find f (0,1). F (x, y) = (1 / (4 π)) * e ^ [- x ^ 2 / 2 - (Y-1) ^ 2 / 8] f (x, y) = FX (x) * FY (y), f (0,1) = FX (0) * FY (1) = 0