In the complete square formula, the quadratic power of (a-b) = the square of a - 2Ab + the square of B, why add the square of B at last I'll work out the square of minus B. (a-b) ^ 2 = (a + (- b)) ^ 2 =a^2+2a(-b)+(-b)^2 Shouldn't the last + (- b) ^ 2 in a ^ 2 + 2A (- b) + (- b) ^ 2 be a ^ 2-2ab-b ^ 2? The minus sign is in parentheses. After calculation, it should be a plus sign to a minus sign. What's the matter, (a-b) (B-A) = {(- a × a) × (- B × b)} is the middle plus or multiply or minus sign. I know the result is - (a-b) &; (a + b) (- a-b) = {(a × - a) × (B × - b)} the result is - (a + b) & # 178; is it an addition or something in the middle.

In the complete square formula, the quadratic power of (a-b) = the square of a - 2Ab + the square of B, why add the square of B at last I'll work out the square of minus B. (a-b) ^ 2 = (a + (- b)) ^ 2 =a^2+2a(-b)+(-b)^2 Shouldn't the last + (- b) ^ 2 in a ^ 2 + 2A (- b) + (- b) ^ 2 be a ^ 2-2ab-b ^ 2? The minus sign is in parentheses. After calculation, it should be a plus sign to a minus sign. What's the matter, (a-b) (B-A) = {(- a × a) × (- B × b)} is the middle plus or multiply or minus sign. I know the result is - (a-b) &; (a + b) (- a-b) = {(a × - a) × (B × - b)} the result is - (a + b) & # 178; is it an addition or something in the middle.

(-b)²
=[(-1)*b]²
=(-1)²*b²
=1*b²
=b²
So it's + B & #178;

Using the complete square formula to calculate the square of (- 1 + 2Ab)

（a+b）^2=a^2+2ab+b^2
(-1+2ab)^2=(-1)^2+2*(-1)*(2ab)+(2ab)^2=1-4ab+4(ab)^2

In the complete square formula, the quadratic power of (a-b) = the square of a - 2Ab + the square of B. why to add the square of B in the end, we should explain it in words and refuse to illustrate it

(a-b)^2
=(a+(-b))^2
=a^2+2a(-b)+(-b)^2
=a^2-2ab+b^2

A number consisting of 10 100, 7 1, 9 0.01 and 0.001 is ()

1007.091

On a map with a scale of 1:5000000, the distance between cities a and B is 8 cm. If you draw on a map with a scale of 1:4000000
What is the distance between a and B in centimeters

Distance = 8 × 5000000 △ 4000000 = 10cm

The gate of a factory, in which the quadrilateral ABCD is rectangular, the upper part is a semicircle with ab as the diameter, in which ad = 2m, ab = 3M, there is a truck full of goods, 8m, 1.8m wide, ask if this car can pass through the gate? And explain the reason

The quadrilateral ABCD is a rectangle, the upper part is a semicircle with ab as the diameter, where ad = 2m, ab = 3M, as shown in the figure, OI = 0.6, OE = 1.5, then EI ^ 2 = OE ^ 2-oi ^ 2. EI = 1.2m, so it can pass

There are 4500 tons of coal, which are divided into three piles of a, B and C. 20 tons are taken from a to pile B, and 30 tons are taken from C to pile B. at this time, a is less than B
There are 4500 tons of coal, which are divided into three piles a, B and C. take 20 tons from a to pile B, and take 30 tons from C to pile B. at this time, a is one eighth less than B, and C is two seventh more than A. how many tons of coal do a, B and C have?

Let a have X tons, B 8 / 7 x tons, C 9 / 7 x tons
It turns out that a has (x + 20) tons, B (8 / 7 x - 50) tons and C (9 / 7 x + 30) tons
There are 4500 tons of coal, and the solution is x = 1312.5 tons
The original a has 1332.5 tons, B has 1450 tons, C has 1717.5 tons

Geometric meaning of Cauchy inequality
Why does this Cauchy inequality show that the cosine of an angle is always less than 1, or that the inner product of two vectors is less than the product of the lengths of two vectors
Make it clear

Let a = (x)_ 1,...,x_ n),b=(y_ 1,...,y_ n) Then = x_ 1 y_ 1 + ...+ x_ n y_ N so | ^ 2 = (∑ x_ i y_ I) ^ 2 by Cauchy inequality, (∑ x)_ i y_ i )^2 ≤ (∑ x_ i^2) (∑ y_ I ^ 2) and | a ^ 2 = = ∑ X_ i^2,|b|^2 = = ∑ y_ I ^ 2

A. B is 320 kilometers away from each other. Car a and car B are going from a and B at the same time. They meet two hours later. It is known that the speed ratio of car a and car B is 7:9. How many kilometers does car B travel per hour?

320 △ 2 × 97 + 9 = 160 × 916 = 90 (km) a: car B travels 90 km per hour

The solution of inequality about x [(M + 3) X-1] (x + 10) > 0
M is less than or equal to 3

Let f (x) = [(M + 3) X-1] (x + 10) = 0, then: x = 1 / (M + 3) or x = - 10 compare: if 1 / (M + 3) ＞ - 10, i.e. m ≤ - 31 / 10: X ∈ (1 / (M + 3), + ∞) ∪ (- ∞, - 10) if 1 / (M + 3) ＜ - 10, i.e. - 31 / 10 ＜ m ≤ 3: X ∈ (- 10, + ∞) ∪ (- ∞, 1 / (M + 3)) if 1 / (M + 3) = - 10, i.e. M = - 31 / 1