ABC is the three sides of △ ABC. When the quadratic function y = (a + b) x ^ 2 + 2cx - (a-b) is x = - 1 / 2, the minimum value - A / 2 is obtained and the triangle shape is obtained Forgive me for being stupid, The chords AB and CD of circle o do not intersect, ab = 6, BC = 8, the sum of degree of two arcs is 180, and the area of two arcs is calculated

ABC is the three sides of △ ABC. When the quadratic function y = (a + b) x ^ 2 + 2cx - (a-b) is x = - 1 / 2, the minimum value - A / 2 is obtained and the triangle shape is obtained Forgive me for being stupid, The chords AB and CD of circle o do not intersect, ab = 6, BC = 8, the sum of degree of two arcs is 180, and the area of two arcs is calculated

When the quadratic function y = (a + b) x ^ 2 + 2cx - (a-b) obtains the minimum value - A / 2 when x = - 1 / 2, we can get y = (a + b) x ^ 2 + 2cx - (a-b) = (x + 1 / 2) ^ 2-A / 2 = x ^ 2 + X + 1 / 4-A / 2, we can get a + B = 12C = 1 - (a-b) = 1 / 4-A / 2 solution, we can get a = 1 / 2, B = 1 / 2, C = 1 / 2, that is △ ABC is equilateral triangle, the side length is 1 / 2

When m > n > 1 (m, n belongs to integer), it is proved that (n · m ^ m) ^ n > (m · n ^ n) ^ m >

That is to say, when n > m > 1, n · ln (n) / (n-1) > m · 1n (m) / (m-1) holds
Construct a function f (x) = x1nx / (x-1) (x > 1)
Then f '(x) = (x-1nx-1) / (x-1) &;
Let g (x) = x-1nx-1 (x > 1), then G '(x) = 1 - (1 / x) = (x-1) / x > 0
The monotonic increase of ∧ g (x) over (1, + ∞)
And G (1) = 0, х g (x) > 0 х f '(x) > 0
The monotonic increase of ∧ f (x) on (1, + ∞)
When n > m > 1, n · ln (n) / (n-1) > m · 1n (m) / (m-1) Note: here, you can change the symbol to understand the thought

In the triangle ABC, ab = AC, BAC = 120 degrees, D is the midpoint of BC, De is perpendicular to AB and E, EB = 3EA is proved
Sorry, I can't do that

Let DB = 2, because the angle B = 30 °, so EB = root 3
AE = root 3, so EB = 3EA

5 square decimeters = () square meters

5 square decimeter = 0.05 square meter
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A rectangular playground, 100 meters long and 75 meters wide. After the expansion, the length and width have increased by a meter. How many square meters has the playground increased@
Tell me about it

After the increase, the length of the playground is 100 + a
The width of the increased playground is 75 + a
Increased playground area: (100 + a) (75 + a)
The increased area of playground: (100 + a) (75 + a) - 100 × 75 = A & # 178; + 175A

There is a triangle with a circumference of 10cm, one side of which is 7cm long and the other side is 10cm long. How many cm is the third side?

I think
It doesn't exist!

A ＠ - 2A of 4-A ＠, where ＠ is the square

（a²-2a）/（4-a²）
=a(a-2)/(2+a)(2-a)
=－a／（a＋2）
It's a minus (a + 2)

Each of the following graphs is a triangle shaped pattern composed of several potted flowers. Each side (including two vertices) has n (n > 1) potted flowers. The total number of pots of each pattern is s. according to this rule, the relationship between S and N is___ ．

When n = 2, s = 1 + 2 = 12 × 2 (2 + 1) = 3; when n = 3, s = 1 + 2 + 3 = 12 × 3 (3 + 1) = 6; when n = 4, s = 1 + 2 + 3 + 4 = 12 × 4 × (4 + 1) = 10 When n = n, s = n (n + 1) 2

What are the characteristics and functions of upper and lower epidermal cells of plant leaves

There is a layer of wax on the upper surface to prevent water evaporation
There are pores in the lower epidermis, gas flow and water evaporation

x3-2x2y+xy2-x

x3-2x2y+xy2-x
=X(X^2-2XY+Y^2)-X
=X(X-Y)^2-X
=X[(X-Y)^2-1]
=X{(X-Y-1)(X-Y+1)]
=X(X-Y-1)(X-Y+1)
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