The square of 2x - 10x = 3 I want formula

The square of 2x - 10x = 3 I want formula

2x²-10x-3=0
△=100+24=124＞0
x=（10±2√31）/4
∴x1=（5+√31）/2,x2=（5-√31）/2

The result of calculating (2x-1) (5x + 2) is ()
A. 10x2-2B. 10x2-5x-2C. 10x2+4x-2D. 10x2-x-2

The original formula = 10x2 + 4x-5x-2 = 10x2-x-2

Given a = x ^ 2-7x-2, B = - 2x ^ 2 + 4x-1, calculation: 1. A + B 2. B + A. A-B 4. B-A

a+b
=x²-7x-2+(-2x²+4x-1)
=x²-7x-2-2x²+4x-1
=-x²-3x-3
b+a
=-2x²+4x-1+x²-7x-2
=-x²-3x-3
a-b
=x²-7x-2-(-2x²+4x-1)
=x²-7x-2+2x²-4x+1
=3x²-11x-1
b-a
=-2x²+4x-1-(x²-7x-2)
=-2x²+4x-1-x²+7x+2
=-3x²+11x+1

There is a jet aircraft with a total mass of m in physics. It is known that the air resistance of the aircraft is proportional to the square of the velocity
There is a jet aircraft with a total mass of M. it is known that the air resistance of the aircraft in flight is directly proportional to the square of the velocity, that is, f = Kv2 (where k is the known quantity). If the fuel consumption of the aircraft in flight can be ignored
(1) When the aircraft is flying horizontally in the air, the upward lift is caused by the different air velocities on the upper and lower surfaces of the wing. If the wing is taken as a reference, the air velocity near the upper surface of the wing is the same________ The velocity of the airflow near the lower surface of the wing
(2) The pressure difference between the upper surface and the lower surface of the aircraft is 0_________ .
The most important thing is the last empty. I really don't understand why mg knows. It's better to tell me the reason in detail

Second question
When the aircraft flies at a constant speed along a horizontal straight line in the air, it means that the force on the aircraft is balanced, while when the aircraft is in the air, it is subjected to two forces in the vertical direction, namely gravity and the pressure on the upper and lower surfaces. Therefore, the pressure on the upper and lower surfaces is equal to the gravity, Mg

Let the air resistance of an aircraft in flight be proportional to the square of its velocity. When the aircraft is flying at constant velocity V, the power of the engine is p. if the aircraft is flying at constant velocity 3V, the power of the engine is ()
A. 3PB. 9PC. 18PD. 27P

When the aircraft is flying at a constant speed, the traction force is equal to the resistance, that is, f = f ′ = Kv2, then the engine power is p = FV = Kv3, that is, the engine power is proportional to the third power of the speed. Therefore, when the speed of the aircraft becomes three times, the engine power becomes 27 times, so option D is positive So D

Let us know that the polynomial ax & sup2; - BX + C, when x = 1, its value is 0; when x = - 2, its value is 1
① Find a root of the quadratic equation AX & sup2; + BX + C = 0 with respect to X

In the original polynomial, the axis of symmetry of the function y = ax & sup2; - BX + C and the axis of symmetry of the function y = ax & sup2; + BX + C are symmetric about the Y axis. A point of the original function (passing through the X axis, (1,0)) is a solution of the equation AX & sup2; - BX + C = 0, that is, x = 1,
So the point of function y = ax & sup2; + BX + C passing through X axis should be symmetric to the original function, that is, passing through (- 1,0)
That is, a root of the equation AX & sup2; + BX + C = 0 is x = - 1

A measuring cylinder is 49cm long and contains 30cm high water. Every time a crow puts a small ball into the measuring cylinder, the water surface rises by 2cm. How many small balls does the water overflow when the measuring cylinder is put into the measuring cylinder?
Tip: is the content of a function, first find the analytical formula, and then calculate
Note: to give the formula!

Let x balls overflow
2X = 49-30
2X=19
X=9.5
So there's water spilling out when you put at least 10 balls in the canister

When 1.4A & sup 2; B + 10ab & sup 2; decomposes a factor, the common factor to be extracted is____ .
2.am+bm=m(____ );-x-1=-(____ );a-b+c=a-(____ ).
3. The common factor of polynomial X & sup2; - 9 and X & sup2; + 6x + 9 is____ .
4. Using diet decomposition calculation: 201 & sup2; - 199 & sup2=____ .
5. If a & sup2; + Ma + 121 is a complete square, then M=____ Or____ .

When 1.4A & sup 2; B + 10ab & sup 2; decomposes a factor, the common factor to be extracted is__ 2ab__ .2.am+bm=m(__ a+b__ );-x-1=-(__ x+1__ );a-b+c=a-(__ b-c__ ）3. The common factor of polynomial X & sup2; - 9 and X & sup2; + 6x + 9 is__ x+3__ 4. Using diet decomposition calculation: 201 & sup2; - 199 & sup2; =

Why is 1 / 300x100% equal to 0.33%? I hope you can write more details!
Why is 1 / 300 0.003333

1/300x100%
≈0.003333x100%
≈0.33%

The square of a number is 6. What is the number
Can the square of a number be zero

± root 6