Trivariate linear equation 3x-y + Z = 4 2x + 3y-z = 12 x + y-2z = 3

Trivariate linear equation 3x-y + Z = 4 2x + 3y-z = 12 x + y-2z = 3

(1) If x = 3 + (2) is 11x + 2Z = 24 (4) (1) + (3) is 4x-z = 7 (5) (4) + (5) × 2 is 19x = 38 ∥ x = 2, substituting x = 2 into (5) is 8-z = 7 ∥ z = 1, substituting x = 2, z = 1 into (3) is 2 + Y-2 = 3Y = 3 ∥ the solution of the system of equations is x = 2Y = 3Z = 1

x-3y-2z=27 2x+3y+z=-5 3x+3y-z=4

x-3y-2z=27 (1)
2x+3y+z=-5 (2)
3x+3y-z=4 (3)
(1) + (2): 3x-z = 22 (4)
(1) + (3): 4x-3z = 31 (5)
(4) X 3 - (5): 5x = 35, x = 7
Substituting (4) into the solution: z = - 1
Substituting the values of X and Z into (3), the solution is y = - 6
Therefore, the solution of the equations is:
x=7
y=-6
z=-1

3ax & # 178; - 3ay & # 178; simplify sisters and brothers

3ax²-3ay²=3a（x²-y²）=3a（x-y）（x+y）

What method does 3ax & # 178; - 3ay & # 178; decompose the factor
The second is 3ay &; 4 power

3ax²-3ay²
=3A (X & # 178; - Y & # 178;) square difference formula
=3a(x+y)(x-y)

The original price of a commodity is 200 yuan. After two price cuts, the current price is 160 yuan. It is known that the second price cut is 1 / 9, and the first one is a discount?
Hurry! Hurry!

160 (1-1 / 9) = 180 (yuan)
180÷200=9/10
So for the first time, 10% off the price

If we know that the function f (x) whose domain is r decreases monotonically at (8, positive infinity) and the function y = f (x + 8) is even, then a.f (6) > F (7) B.F (6) > F (7) B
If we know that the function f (x) whose domain is r decreases monotonically at (8, positive infinity) and the function y = f (x + 8) is even, then
A.f（6）＞f（7）
B.f(6)＞f(9)
C.f(7)＞f(9)
D.f（7）＞f(10)
The main problem is the relationship between F (x) and y = f (x + 8)
Some people say that f (x + 8) is obtained by moving f (x) 8 units to the left. Why? Or is it a conclusion? How to prove it?

Translation depends on how the corresponding point on the function moves
Suppose f (0) is equal to a number called G, then in y = f (x + 8), when x = - 8, y = g, that is (- 8, g) is on the function; in y = f (x), when x = 0, y = g, (0, g) is on the function. So it is equivalent to moving (- 8, g) to (0, g)
The other points are the same
There is a formula
Left plus right minus, top plus bottom minus
It's adding a few units. It's moving the image to the left or up a few units

It takes 10 minutes to divide a piece of wood into 40 cm long segments. It is known that it takes 1 minute to saw off a segment, which is the same as how long is the wood?
(we need the formula! We can't use * /, we can only use × / X!)

10 △ 1 = 10 times [saw 10 times in total]
10 + 1 = 11 segments [a total of 11 segments]
11 × 40 = 440cm
440cm = 4.4m
A: this wood is 4.4 meters long

The price of a product is reduced by 10% during the promotion period, and then increased by 10% after the promotion______ ．

100 × (1-10%) × (1 + 10%), = 90 × 1.1; = 99 (yuan); so the stem of the question is wrong

Given A-B = 8, ab = 9, find the value of a ^ 2 + B ^ 2-3ab

The original formula of formula = A2 + b2-2ab-ab = (a + b) 2-AB, and then substitute into the square of 8 - 9 = 55

( ⊙ o ⊙
①（-85）×（-25）×（-4）
② (- 7 / 8) × 15 × (- 1 / 7)
③ (9 / 10-1 / 15) × 30

①（-85）×（-25）×（-4）
=-85*(25*4)=-8500
② (- 7 / 8) × 15 × (- 1 / 7)
=(-7/8)(-8/7)*15=15
③ (9 / 10-1 / 15) × 30
=9/10*30-1/15*30
=27-2=25