11x+3z=9 2x+2y+z=8 2x-6y+4z=5 The linear equation of three variables

11x+3z=9 2x+2y+z=8 2x-6y+4z=5 The linear equation of three variables

11x + 3Z = 9, 1 2x + 2Y + Z = 8, 2 2x-6y + 4Z = 5, 2 * 3: 6x + 6y + 3Z = 24, 4 + 4: 8x + 7z = 29, 5 * 3: 24x + 21z = 87, 6 1 * 7: 77X + 21z = 63, 7 7 - 6: 53x = - 24, that is, substituting x = - 24 / 53 into 1, we get z = 247 / 53x = - 24 / 53, substituting z = 247 / 53 into 2, we get y = 225 / 106

Han Zhixian's family bought a house in Hefei. After decoration, Zhixian found that his floor was composed of three regular polygons. Let the number of sides of the three regular polygons be a, B and C respectively. Try to find one in a + one in B + one in C
In △ ABC, BD bisects ∠ ABC, CD bisects the outer angle ∠ ace of △ ABC, and BD and CD intersect at point D
When ∠ a = 40 °, 90 ° and 126 °, please calculate the degree of ∠ D respectively

1.
There are three ways to combine regular polygons into a plane
1) One regular triangle, two regular quadrilaterals and one regular hexagon
2) One regular quadrilateral, one regular hexagon and one regular dodecagon
3) Regular triangle, regular quadrilateral and regular dodecagon
1)
1/3+1/4+1/6
=4/12+3/12+2/12
=9/12
=3/4
2)
1/4+1/6+1/12
=3/12+2/12+1/12
=7/12
3)
1/3+1/4+1/12
=4/12+3/12+1/12
=8/12
=2/3
two
The outer angle of a triangle is equal to the sum of the other two angles of the triangle
∠DCE=∠CBD+CDB
Double two on both sides
2∠DCE=2∠CBD+2∠D
∠ACE=∠ABC+2∠D
And because
∠ACE=∠ABC+∠A
==>
∠A=2∠D
When ∠ a = 40 °, 90 ° and 126 °
∠D=20°,45°,63°
Make up

There are two questions. The original title is as follows:
It is known that the equation of X: (2kx + A / 3) = 2 + [(x-bk) / 6] (where a, B and K are constants)
① If the equation has no solution, then what is the value of K?
② If K is any value, the root of the equation is always 1, try to find the value of a and B

Simple: after simplifying the equation from left to right: 12kx + 2A = 12-bx + 2A shift: (12k-1) x = 12-bx + 2A the first question is solved: 12k-1 = 0, k = 1 / 12 the second question is not difficult: replace x = 1 into the original formula to simplify 12K + 2A = 13-bk the same unknowns shift and merge: (12 + b) k = 13 + 2A the problem means that K value is indefinite, then the left and right of the equation are all

A is a natural number greater than 0. When a equals (), it is a true fraction. When a equals (), it is a false fraction. When a equals (), it is equal to 3

1. When a = (6), 5 / A is the largest true fraction; when a = (5), 5 / A is the smallest false fraction; when a = (15), a / 5 is equal to 3.2, take a / 2 as an example
It is a false fraction when a = 2
When a = 6, it is equal to 3

The relationship between rational numbers, irrational numbers, integers, natural numbers, real numbers, etc. and whether they include 0. Negative numbers
Such as the title

Integers and fractions (finite decimals) are collectively referred to as rational numbers -- (rational numbers are divided into integers -- (integers are divided into positive integers, negative integers and 0) and fractions -- (fractions are divided into positive fractions and negative fractions)) infinite acyclic decimals and numbers with endless open roots are called irrational numbers. Real numbers include rational numbers and irrational numbers. Positive integers and 0 are also called natural numbers -- natural numbers are integers greater than or equal to 0 Rational numbers have zero and negative numbers, irrational numbers have no zero but negative numbers, integers have zero and negative numbers, natural numbers have zero but no negative numbers, real numbers have zero and negative numbers

Find the rules and fill in the numbers. 2,3,4,6,8, (), 16,12
Find a rule and fill in a number in brackets
2,3,4,6,8,(),16,12
I also want to know why

9
It's easy to find one after another

Proof: for natural number n, 2n + 4-2n can be divided by 30

2^(n+4)-2^n
=2^n(2^4-1)
=2^n*15
=30*2^(n-1)
30*2^(n-1)/30=2^(n-1)
2n + 4-2n can be divided by 30

If the image of exponential function f (x) passes through (2,9), then f (1) - f (- 2)=

f(x)=3^x
f(1)=3
f(-2)=1/9
f(1)-f(-2)=3-1/9=26/27

I don't know ____ to do next A what B how
I don't know ____ to do next
A what B how C why DWhere

a
Hope to adopt
what to do=how to do it

Factorization of (M + 4) (m-2) + 9

(m+4)(m-2)+9=m^2+2m-8+9=m^2+2m+1=(m+1)^2