Is kg a unit of weight or a unit of mass? If it's a unit of mass, why do you sometimes use kg when it's heavy?

Kg is the unit of mass. It's used to saying how much something weighs in our daily life. In physics, the exact mass should be called. As we all know that "how much" means mass, we don't need to be precise. But in physics, it's better to be precise

Finding the negative integer solution of the quadratic equation 3x + y = - 8

There is more than one, x = - 2, y = - 2; X = - 1, y = - 5;

Four students went to plant trees. The first student planted 12 trees, the second 14 trees, the third 15 trees, and the fourth 15 trees. How many trees did the four students plant?

15 (1-11 + 2-11 + 4-11 + 5) = 15 (1-13-15-16) = 15 (310) = 15 × 103 = 50 (trees) a: the four students planted 50 trees

If x is a rational number, then the square of lxlx = 1 LX + 1L must be a positive number

It should be: X & # 178; + 1
The rest can be equal to zero

1. 2. Xiaoming deposits the 4000 yuan lucky money in the bank for 2 years. If the annual interest rate is 4.25%, the total amount of principal and interest of Xiaoming should be listed

Question 1: 2 * 24 * 3.5-144 = 168-144 = 24
Question 2: 4000 + 4000 * 4.25% * 2 = 4000 + 170 = 4170

What is the solution of equation x squared - 4x = 0

There are three solutions for y = x ^ 2-4x
1. If x ^ 2 = 4x and both sides divide x, we can get x = 4 or 0 2. If x (x-4) = 0, we can get x = 0 or 4 3. If x 1 = 4, we can get x 2 = 0

This problem is solved by equation. The distance between a and B is 720 kilometers. A bus and a freight car start from a and B at the same time and travel in opposite directions. The bus travels 100 kilometers per hour
The truck runs 80 kilometers per hour. How many hours later do the two cars meet?
Please answer by half past six tonight.

Let's meet in X hours
100x+80x=720
x=4
A: meet in 4 hours

(1 + 1 / 3) x equals 4 / 5

(1 / 2 + 1 / 3) △ 2 / 5-3 / 4
=5/6×5/2-3/4
=25/12-9/12
=16/12
=4/3
5 x = 3 0.8
3x=4
x=4/3

The walking speed ratio of a and B is 13:11. If a and B walk from a, B and two places at the same time, and meet in two hours, if they walk in the same direction, then
It takes () hours for a to catch up with B

It takes (24) hours for a to catch up with B
(13+11)x2÷(13-11)=48÷2=24

Solution equation: 2x + 5 (X-2) = 60

2x+5x-10=60
2x+5x=60+10
7x=70
x=10

Is kg a unit of weight or a unit of mass? If it's a unit of mass, why do you sometimes use kg when it's heavy?