When solving the system of linear equations of three variables: x + 2Y = 8,2-3y + 2Z = 5, x + 2y-z = 3, it is easy to eliminate the unknown number () first

When solving the system of linear equations of three variables: x + 2Y = 8,2-3y + 2Z = 5, x + 2y-z = 3, it is easy to eliminate the unknown number () first

Subtracting formula 3 from Formula 1, eliminating X and Y first is the simplest, then we can get z = 5, bring in formula 2 to get y, and bring in Formula 1 to get X

To solve the equations: x + 3Y = 113x + 2Y = 12

X + 3Y = 11, ① 3x + 2Y = 12, ② ① × 3: 3x + 9y = 33, ③ - ②: 7Y = 21, y = 3, substituting y = 3 into ①: x + 3 × 3 = 11, x = 2. So the solution of the original equations is x = 2Y = 3

Finding the positive number solution of the quadratic equation 3x + 2Y = 24

x=2 y=9 ,
x=4 y=6,
x=6 y=3.

The two forces acting on the same point are F1 = 5N and F2 = 4N. If the angle between the resultant force F and F1 is θ, then θ may be ()
A. 30°B. 45°C. 60°D. 75°

According to the trigonometric rule, two forces F1 and F2, the resultant force F, as shown in the figure, are obtained according to the geometric knowledge. When F2 is perpendicular to the resultant force F, θ is the largest. If the maximum value of θ is θ m, then sin θ M = f2f1 = 45, θ M = 53 °, so θ may be 30 ° and 45 °

The sum of two times of a number and three is one half of the sum of the number and three

2x+3=1/2(x+3)
x=-1

The size of the friction is related to the way the object moves. For the same object, the rolling friction is greater_ The friction force of sliding

Smaller, larger

Is 1 / x = 8 a linear equation with one variable?

An equation with only one unknown number and the highest degree of the unknown number is one is called one variable linear equation. The usual form is ax + B = 0 (a, B are constants, and a ≠ 0). One variable linear equation belongs to integral equation, that is, both sides of the equation are integral. One variable means that the equation has only one unknown number and the degree of one time is 1, Let's call ax + B = 0 (where x is the unknown, a and B are known numbers, and a ≠ 0) the standard form of the linear equation with one variable. Here a is the coefficient of the unknown, B is a constant, and the degree of X must be 1. The degree of the unknown above is - 1, so it does not belong to the linear equation with one variable

A car runs between a and B for 4 hours. It is known that the speed of the car is 45 km / h and the speed of the car is 30 km / h
30 = 45 = 75 45 / 75 = 45 of 75 30 * (45 of 75 * 4) = 72 (km)
I'll wait 20 minutes at most,

If the distance is set to s:
s/45+s/30=4
In the process of calculation, your formula appears, but it has no practical significance to extract your formula. The answer is 72

(4.1) ^ (2 / 5), 3.8 ^ (- 2 / 3) and (- 1.9) ^ (- 3 / 5),

Because 4.1 > 1, (4.1) ^ (2 / 5) > 1 ^ (2 / 5) = 1; 3.8 ^ (- 2 / 3) = [3.8 ^ (- 1)] ^ (2 / 3), and 3.8 ^ (- 1) 3.8 ^ (- 2 / 3) > (- 1.9) ^ (- 3 / 5)

102 square + 98 square with factorization

102 square + 98 square
=(102+98)²-2*102*98
=200²-2*(100+2)(100-2)
=40000-2*(10000-4)
=20000+8
=20008