If two intersecting planes are perpendicular to the third plane at the same time, then the intersection line of the two intersecting planes is perpendicular to the third plane. Can this be used as a judgment theorem? High school textbooks don't have this theorem, so we need to write a lot when proving it! But if two intersecting planes are perpendicular to the third plane at the same time, their intersection line should also be perpendicular to the third plane. Can we judge it directly as a theorem?

High school textbooks do not have this theorem, can not be directly used as a decision theorem

Given the two ball equation: x2 + Y2 + Z2 = 1, X2 + (Y-1) 2 + (Z-1) 2 = 1, find the projection of their suburban intersection C on xoy plane

On the xoy plane,
x²+y²+z²=1
X & sup2; + (Y-1) & sup2; + (Z-1) & sup2; = 1
Just eliminate Z
X & sup2; + Y & sup2; + (1-y) & sup2; = 1, that is, X & sup2; + 2Y & sup2; - 2Y = 0

There is a column of numbers A1, A2, A3, A4, A5 Where a1 = 5 × 2 + 1, A2 = 5 × 3 + 2, A3 = 5 × 4 + 3, A4 = 5 × 5 + 4, A5 = 5 × 6 + 5 When an = 2009, the value of n is equal to______ ．

According to the meaning of the question, when an = 2009, that is 5 × (n + 1) + n = 2009, the solution is n = 334

3.14x divided by 2 + x = 10.28

3.14x divided by 2 + x = 10.28
1.57x+x=10.28
2.57x=10.28
x=10.28÷2.57
x=4

LINGO min 45;(x1+x2) ST x1+x2>=1 x1
min 45;(x1+x2)
ST
x1+x2>=1
x1

model:
min=45/(x1+x2);
x1+x2>=1;
x1

-4X & # 178; + 5x + 5 can be written as ascending power_ The polynomial-2 / 5 x & # 178; y + XY + 2x-1 is Times Item form
-4X & # 178; + 5x + 5 can be written as ascending power_
The polynomial-2 / 5 x & # 178; y + XY + 2x-1 is Times Item form
Given a three digit number, its hundred digit number is a, ten digit number is B, and one digit number is C, and a < C, transpose the position of a and C, what is the difference between the original number and the present number? Can it be divided by 99?

-4X & # 178; + 5x + 5 can be written as ascending power___ 5+5x-x²
The polynomial-2 / 5 x & # 178; y + XY + 2x-1 is_ 3_ Times_ 4_ Item form
Given a three digit number, its hundred digit number is a, ten digit number is B, and one digit number is C, and a < C, transpose the position of a and C, what is the difference between the original number and the present number? Can it be divided by 99?
100a+10b+c-(a+10b+100c)
=99a-99c
=99(a-c)
It is divisible by 99

In the circle O, there is a chord Mn, which connects OM and on to make the angle omn 90 degrees. Take the midpoint a of Mn as AB, which is parallel to the intersection of on and B to find the degree of the angle bon

30 degrees
Let AB intersect om with E
∵ AB is parallel to on
∴∠OEB=∠MEB=∠MON=90°
Triangle OEB is right triangle
And point a is the midpoint of Mn
The midpoint of OM is e
∴OE=OM/2=OB/2
∴BON=∠EBO=30°

2 * 8 to the power of M * 8 to the power of M * 16 to the power of M = 4

2 * 8 to the power of M * 8 to the power of M * 16 to the power of M
=2^(1+3m)*2^4m
=2^(1+7m) 4^11=2^22
2^(1+7m) =2^22
1+7m=22
m=3

How many wires and switches are used for 40 kW equipment?

It depends on the type of equipment. For example, the motor and heating are different. There are many kinds of switches. There is a certain relationship between the current that the wire bears and the ambient temperature, and whether it passes through the pipe. If it is a three-phase 380V, the heating equipment, 40kW / 380V = 105.3a, 105.3a / 1.732 = 60.8a, can be used continuously for a long time, and about 30 square copper wire can be selected

On the equation (3m-1) x = 6x-35 of X, if the solution of the equation is a negative integer, find the maximum value of M

(3m-1)x-6x=-35
(3m-7)x=-35
x=-35/(3m-7)
Because its solution is a negative integer, 1 ≤ 3m-7 ≤ 35
So 8 / 3 ≤ 3m-7 ≤ 14
The maximum value of M is 14