What is the formula of the distance between point to point, point to line and line to line

Point to point: let two points (x1, Y1) (X2, Y2) d = √ (x1-x2) ^ 2 + (y1-y2) ^ 2
Point to line: set point (x1, Y1) straight line ax + by + C = 0
▕Ax1+By1+C▕
d= -------------
√A^2+B^2

It is known that a = x2 + 1 / 2, B = 2-x, C = x2-x + 1. It is proved that at least one of a.b.c. is not less than 1

It is proved that if a, B and C are all less than 1, then B = 2-x1, then a = x ^ 2 + 1 / 2 > 1, which contradicts the hypothesis
Therefore, a, B, C can not all be less than 1, that is, at least one of a, B, C is not less than 1

We all know the formula of the second derivative d ^ 2Y / DX ^ 2. How to use this formula for y = x ^ 2?
Is d^2y/dx^2 as like as two peas, y'', and the same applies?

First, find the first derivative dy / DX = 2x
The second derivative is D & # 178; Y / DX & # 178; = D (dy / DX) / DX = 2

What is the formula of projective theorem

Projective theorem of right triangle (also known as Euclid theorem): in a right triangle, the height of the hypotenuse is the middle term of the proportion of the projection of two right sides on the hypotenuse. Each right side is the middle term of the projection of the right side on the hypotenuse and the proportion of the hypotenuse
In the formula RT △ ABC, ∠ BAC = 90 ° ad is the height on the hypotenuse BC, then there is a projective theorem as follows: (1) (AD) ^ 2; = BD · DC, (2) (AB) ^ 2; = BD · BC,
(3) (AC) ^ 2; = CD · BC. Equal product formula (4) abxac = bcxad (can be proved by area) projective theorem of arbitrary triangle, also known as "first cosine theorem": △ ABC's three sides are a, B and C, and their opposite angles are a, B and C respectively, then a = B · COSC + C · CoSb, B = C · cosa + a · COSC, C = a · CoSb + B · cosa. Note: Taking "a = B · COSC + C · CoSb" as an example, the projective of B and C on a are B · COSC and C · CoSb respectively, Hence the name projective theorem

If f (z) = u + IV is an analytic function, u = x ^ 3-3xy ^ 2, f (0) = 0, find f (z)

No high standard to him, go to her, give her

If the function f (x) has a second derivative in (a, b), and f (x1) = f (x2) = f (x3), where a

The second derivative of F (x) exists. The first derivative of F (x) exists. F (x) is continuous. F (x) is continuous on [x1, X2] and differentiable in (x1, x2). According to Rolle's theorem, there is at least one C1 belonging to (x1, x2) such that f '(C1) = 0. Similarly, f (x) is continuous on [X2, X3] and differentiable in (X2, x3)

After adding m to the numerator and denominator of 29 / 5 of the fraction, the ratio of numerator to denominator is 19:7
(29-5) / (7-1 out of 19) - 5, but I don't know why,

There is a problem with your answer. The result of your calculation is negative. If it is 5 out of 29, it is negative. Your question is 29 out of 5. According to your question 29 + m / 5 + M = 19 / 7 95 + 19m = 203 + 7m 12m = 108

Solving differential equation y "xlnx = y '

dy'/dx*xlnx=y'
dy'/y'=dx/(xlnx)
Integral on both sides: ln | y '| = ln | LNX | + C1
That is y '= c1lnx
Two side integral: y = C1 ∫ lnxdx = c1xlnx-c1 ∫ x * DX / x = c1xlnx-c1x + C2 = c1x (lnx-1) + C2

1 / 1,7 / 8,5 / 6,13 / 16 () 4 / 5 () 19 / 24 to explore the fifth and fourth law

The questions are: 1 / 1,7 / 8,5 / 6,13 / 16, (), 19 / 24, explore the law and find the fifth number
Answer: the fifth number (4 / 5)
When the original sequence is rewritten, the law is found
1 / 1, 7 / 8, 5 / 6, 13 / 16, (4 / 5), 19 / 24 are rewritten as follows:
4/4,7/8,10/12,13/16,(16/20),19/24
General term: an = [4 + 3 (n-1)] / [4 + 4 (n-1)]
a5=16/20=4/5

In the following multiplication formula, the same letter represents the same number, and different letters represent different numbers. You can change all letters into numbers to make the formula hold
A B C
× D C

B E A
F A G H
__
F I G A A

I've been counting for a long time, but your seat is not right

What is the formula of the distance between point to point, point to line and line to line