There is a pile of coal in the canteen, which weighs 1.78 tons. After burning for a week, there is still 0.38 tons left. How many tons do you burn every day

There is a pile of coal in the canteen, which weighs 1.78 tons. After burning for a week, there is still 0.38 tons left. How many tons do you burn every day

Set an average of X tons per day
7x+0.38=1.78
7x=1.78-0.38
7x=1.4
x=0.2
A: an average of 0.2 tons per day

10: Is 2 / 3 = 1 / 2:1 / 3 an equation

Of course, the solution is x = 1

How does (x + 3) (x-1) - x (- 2) decompose the equation?

x^2+4x-3

Finding the domain of definition of function f (x) = LG (2x-3) + (x-4 of 2)

The solution to the problem is 2x-3 ＞ 0 and 2 ^ x-4 ≠ 0
That is, X ＞ 3 / 2 and X ≠ 2
So the definition field of function is {X / X ＞ 3 / 2 and X ≠ 2}

The vertex coordinates of parabola y = 0.5x ^ 2 + 6 are

（0,6）

The rational numbers a, B, C are not 0, and a + B + C = 0. Let x = ||||a | / B + C + ||b | / C + A + ||c | / A + B |, try to find the value of the 19th power - 99x + 2104 of the algebraic formula X
The process is more detailed_ ∩)O

X = ||a | / (B + C) + |b | / (c + a) + |c | / (a + b) |, is the problem x like this? If so, the solution is as follows:
x=||a|/(-a)+|b|/(-b)+|c|/(-c)| （1）
∵ rational numbers a, B, C are not 0, and a + B + C = 0
Then there must be one negative number or two negative numbers in a, B and C,
1) When there is only one negative number, let A0, C > 0
Then (1) is | 1-1-1 | = 1
2) When there are two negative numbers, let a

(5x-1200)/(4x-1000)=13/10

(5x-1200)*10=(4x-1000)*13
50x-12000=52x-13000
2x=1000
x=500

1. Train a and train B leave 450 kilometers away from each other at the same time, and they meet five hours later. Train a travels 55 kilometers per hour, and train B how many kilometers per hour?
Equivalency relationship:______________________________
2. A barrel of diesel oil weighs 120 kg. After 3 / 4 of the oil is poured out, the barrel weighs 45 kg. How many kg is the barrel of diesel oil?
3. In a two-tier bookshelf, the number of books on the upper shelf is three times that on the lower shelf. If 60 books on the upper shelf are moved to the lower shelf, the books on the two shelves are equal. How many books are there on the upper shelf and the lower shelf?
4. When the bus goes from place a to place B, it travels 60 kilometers per hour, one hour earlier than the planned time. When it returns, it travels 40 kilometers per hour, one hour later than the planned time. How many hours do you plan to arrive?
5. In a division formula, the quotient is 18, and the sum of divisor and divisor is 361?
The first and second problems must be solved by equations

1. Set car B to travel x kilometers per hour
5（55+X）=450
55+X =90
X=35
2. Suppose that the barrel of diesel oil used to be x kg
45+3/4X=120
3/4X=75
X=100
3. Lower layer 60 * 2 / 3 = 40 (this)
Upper layer 40 * 3 = 120 (this)
4. (60 + 40) / (60-40) = 5 (hours)
5. Divisor: 361 / (18 + 1) = 19
After half a day's work, I can't give you some branches

To solve an equation (a-2x) (b-2x) = AB about X

(a-2x)(b-2x)=ab
Take the equation apart
ab-2ax-2bx+4x²=ab
transposition:
4x²-2ax-2bx=0
Simplification:
2x²-ax-bx=0
Extract the common factor X:
x（2x-a-b）=0
The solution is: x = 0
Or x = (a + b) / 2

When calculating mixed operation with ordinary calculator, input it from left to right___ (judge right or wrong)

When using ordinary calculator to calculate mixed operation, the second level operation is calculated first, and then the first level operation is calculated