Is the complete square formula a square + b square - 2Ab equal to (a-b) square or (B-A) square

Is the complete square formula a square + b square - 2Ab equal to (a-b) square or (B-A) square

In fact, the square of (a-b) is the same as that of (B-A) because it will be positive after the square

5 / A + 1 is equal to 2 / Y-3 3A + 4Y is equal to 32 to solve binary linear equation

First go to the denominator and then use the substitution method to get the result
a=4
y=5

If the solution of the quadratic simultaneous equation 2x − y = 33x − 4Y = 3 is x = a, y = B, then a + B = ()
A. 1B. 6C. 35D. 125

∵ 2x-y = 3, ∵ y = 2x-3, ∵ 3x-4 × (2x-3) = 3, ∵ x = 95, ∵ y = 2 × 95-3 = 35. ∵ x = a, y = B, ∵ a + B = x + y = 95 + 35 = 125

The two passenger and freight cars start from the two places of a and B and run in opposite directions. The speed ratio of the passenger car to the freight car is 6:5. After driving for several hours, the passenger car and the freight car meet. At this time, the train is 30km away from the midpoint. Ask the distance between the two places

When they met, the bus traveled 30x2 = 60km more than the truck
The distance between the two cities is 60 ÷ (6-5) x (6 + 5) = 660km
A: the two cities are 660 kilometers apart
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Let a = x ^ 2-x + 1, B = x ^ 2-2x, C = 2x-1. If ABC is the corresponding three sides of △ ABC, find the value range of real number x and the maximum inner angle of △ ABC

(1) Using the sum of the two sides of the triangle is greater than the third side, the range of X is obtained
① B + C > A, that is, B + C-A > 0, X-2 > 0, the solution is x > 2
② A + C > b, that is, a + C-B > 0, 3x > 0, the solution is x > 0
③ A + b > C, that is, a + B-C > 0, (2x-1) (X-2) > 0, the solution is x < 1 / 2 or x > 2
To sum up, the value range of X is x > 2

There are 240 people in the two engineering teams. If one tenth of team a is transferred to team B, the ratio of team a and team B is 9:7. How many people are there in each team?

Now a = 240 * 9 / 16 = 135
Original a = 135 (1-1 / 10) = 150
B = 240-150 = 90

What is the digital sum of all natural numbers from 15 to 2004?
The answer is 27960, but I don't know how to calculate, the calculation process and (formula)!

In order to simplify the formula, the following symbols are defined: the sum of 1 to 10 ^ n-1 (natural number n 9) is Sn, so it is easy to deduce Sn = 45 * n * 10 ^ (n-1); the sum of each digit of n-digit number an = ∑ AI * 10 ^ (i-1) is Sn, AI is the i-th digit of an, I from 1 to N; the natural number of an after removing the highest digit is a

17. Passenger cars travel 100 kilometers per hour, and passenger cars 80 kilometers per hour. (1) if two cars go to Jiadi in the same direction at the same time, how many kilometers is the distance between the two cars after 5 hours? (2) if they travel in opposite directions, how many kilometers is the distance between the two cars after 3 hours?

(1) (100-80) * 5 = 100 km
(2) (100 + 80) * 3 = 540km

In the triangle ABC, BD and CE are two high lines. Prove that B, C, D and E are on a circle

Take the midpoint F of BC
Connecting DF and ef
Because BD and CE are the two heights of triangle ABC
In right triangle BCE and BCD, EF and DF are the midlines of their hypotenuse BC respectively
Because in a right triangle, the center line on the hypotenuse is half of the hypotenuse
So there are: EF = DF = BF = CF = 1 / 2BC
So the four points B, C, D and F are on the circle with F as the center and 1 / 2BC as the radius

A. B is 780 km away from the two places. Buses and cars start from the two places at the same time and run in opposite directions. They meet in six hours. Cars are 40 km faster than trains. How many kilometers are they

780÷6= 130
(130-40) △ 2 = 90 △ 2 = 45 (km / h)
45 + 40 = 85 (km / h)
This is their speed
I don't know if you want their speed?
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