How to deduce the direction vector of the straight line, CX AZ = CX * and CY BZ = CY *|

How to deduce the direction vector of the straight line, CX AZ = CX * and CY BZ = CY *|

The normal vectors of the plane CX AZ = CX * and CY BZ = CY * are
(C, 0, - a) and (0, C, - b)
Their cross product is a vector in the direction of a straight line

What is the least common multiple of 45 and 135? What is the least common multiple of 48, 16 and 24?
I want to do a problem

135 and 48, respectively

How to find all the formulas of pressure

Pressure is a force acting perpendicular to the surface of an object
The object is still on a horizontal plane, and the pressure on the opposite side is equal to g
Know the pressure, find the pressure: F = PS
Or: F = ρ GHS (liquid)
If it's high school, it's related to the inclination of the plane or the angle of the force

Finding the extremum of function f (x, y) = 1 / 2x ^ 2-xy + y ^ 2 + 3x

fx=x-y+3=0
fy=-x+2y=0
Solution
Unique stationary point (- 6, - 3)
A=fxx=1
B=fxy=-1
C=fyy=2
AC-B²=1>0,A>0
therefore
Take the minimum f (- 6, - 3) = - 9

What is the difference between the molecules that make up ice and those that make up water vapor?
The molecules that make up ice and the molecules that make up water vapor have different properties______ . a. the same properties B. the same physical properties C. the same chemical properties D. different chemical properties hope to get your help!

b

The meaning of the letter should be put on

a=(Vt-Vo)/t
A -- acceleration
Vt -- final velocity
VO -- initial velocity
T -- the time that the speed of an object changes

A math problem in log
Log3 1 / 64 × log4 √ 5 × Log1 / 25 27 √ 5 is the root sign and 5 × is the multiplication sign
=log3 2^(-6) ×log2^2 5^(1/2) ×log5^(-2) 3^3
=[(-6)×log3 2] ×[(1/2)×(1/2)×log2 5] ×[(-1/2)×3×log5 3]
This is how to convert the base number can also be placed in the front
For example, log2 ^ 2 ^ 3 can be put in front, I know, but why is 2 ^ 2 put in front

log3 1/64×log4 √5×log1/25 27
=log3 2^(-6) ×log2^2 5^(1/2) ×log5^(-2) 3^3
=[(-6)×log3 2] ×[(1/2)×(1/2)×log2 5] ×[(-1/2)×3×log5 3]
=[(-6)×(1/2)×(1/2)×(-1/2)×3]×[log3 2×log2 5×log5 3]
=9/4 ×[lg3/lg2 × lg2/lg5 ×lg5/lg3]
=9/4
If the true number is in the form of the nth power of a number, then n can be multiplied to the front of log;
If the base of logarithm is in the form of n power of a number, the reciprocal of N can be multiplied to the front of log

Simple calculation: 1 * 2 / 1 + 2 * 3 / 1 + 3 * 4 / 1 ····· + 38 * 39 / 1 + 39 * 40 / 1
1 * 3 / 1 + 3 * 5 / 1 + 5 * 7 / 1 + ······ + 19 * 21 / 1 + 21 * 23 / 1
Note: the score is like this
one
——
1*2

1/[n*(n+1)]=1/n-1/(n+1)
1 * 2:1 + 2 * 3:1 + 3 * 4:1 ····· + 38 * 39:1 + 39 * 40:1
=1/1-1/2+1/2-1/3+1/3-1/4.+1/38-1/39+1/39-1/40
=1-1/40
=39/40
1/[n*(n+2)]=1/2*[1/n-1/(n+2)]
1 * 3 / 1 + 3 * 5 / 1 + 5 * 7 / 1 + ······ + 19 * 21 / 1 + 21 * 23 / 1
=1/2*(1/1-1/3)+1/2*(1/3-1/5).+1/2*(1/19-1/21)+1/2*(1/21-1/23)
=1/2(1/1-1/3+1/3-1/5+.+1/19-1/21+1/21-1/23)
=1/2(1-1/23)
=1/2*22/23
=11/23

Odd language: is the product of even number or even number? Is the product of odd number and odd number odd or even? Is even a product of even number?

The product of an even number is an even number
The product of odd and odd numbers is odd
The product of even numbers is even

8-2 / 3-2 / 15-2 / 35-2 / 63-2 / 99-2 / 143-2 / 195-2 / 255
8-2 / 3-2 / 15-2 / 35-2 / 63-2 / 99-2 / 143-2 / 195-2 / 255

=8-(1-1/3)-(1/3-1/5)-(1/5-1/7)-(1/7-1/9)-(1/9-1/11)-(1/11-1/13)-(1/13-1/15)-(1/15-1/17)
=8-1+1/17
=7+1/17
=120/17