The solution set of inequality-5 < x-3 ≤ 2 is

The solution set of inequality-5 < x-3 ≤ 2 is

-5

Solving inequality: 3 (x + 2) - 6 ≤ 5 (2-x) + 2

3（x+2）-6≤5（2-x）+2
3x+6-6≤10-5x+2
8x≤12
x≤1.5

Solve this inequality: x-3 > 1-x, X-5 > 5-x / 2, x-4 > x / 2

2x＞4,x＞2
1.5x＞10,x＞20/3
0.5x＞4,x＞8

More than 100 words of mathematician's story

When Gauss was in primary school, once after the teacher taught addition, because the teacher wanted to have a rest, he gave a question to the students to calculate. The question was: 1 + 2 + 3 +. + 97 + 98 + 99 + 100 =? The teacher thought, now the children must calculate until the end of the class! When he was about to go out, he was stopped by Gauss! Originally, Gauss has worked it out, Do you know how he calculates it? Gauss tells you how he calculates it: add 1 to 100 and 100 to 1 in two rows, that is, 1 + 2 + 3 + 4 +. + 96 + 97 + 98 + 99 + 100, 100 + 99 + 98 + 97 + 96 +. + 4 + 3 + 2 + 1 = 101 + 101 + 101 +. + 101 + 101 + 101 + 101 + 101, there are 100 101 in total, but the formula is repeated twice, So dividing 10100 by 2 will get the answer, which means that the learning process of Gauss primary school has already surpassed other students since then, which has laid the foundation for his future mathematics and made him a mathematical genius!
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Unit price fabric: 48 / kg / kg = 5.5 m, door width: 1.65 m, length: 150 cm, width: 50 cm, how much is the fabric cost of a scarf

The actual cost price of a scarf is 3.97 yuan, which should be multiplied by 5% loss, which can be equal to 4.17 yuan
Details are as follows: 48 / 5.5 = 8.73 yuan (price per meter)
The size of a scarf is: 1.5 * 0.5 = 0.75
1 * 1.65/0.75 = 2.2 (1 meter cloth can make 2.2 scarves)
8.73 / 2.2 * 1.05 = 4.17 yuan
If not, ask me again

A trapezoid formed by an equilateral triangle of the same size, please divide the trapezoid into five small trapezoids of the same size, how to divide, please give some tips to experts, thank you

The top three short line segments, two long line segments staggered
There are three long segments below, and two segments are staggered
Connect the top and bottom of the line, success!

Is angle an axisymmetric figure?
Since the two sides of the angle are infinitely extended, they are not necessarily symmetrical
I don't mean the size of the angle. I mean, axisymmetry doesn't have to be completely coincident? If it is infinitely extended, it doesn't have to be coincident

An angle is indeed an axisymmetric figure. Its axis of symmetry is the bisector of an angle. After learning to draw with rulers and compasses, we know that every angle has bisector, so an angle is an axisymmetric figure
In addition, the infinite extension of the two sides of the angle does not affect the size of the angle, so it is not related

The substitution elimination method and addition and subtraction elimination method are used to solve the equations x + y = 7,5x + 3Y = 31 respectively, and the common points of the two methods are explained

Substitution elimination method:
Convert x to x = 7-y
Substituting into the two formulas, we get 5x (7-y) + 3Y = 31
The solution is y = 2, and the substitution is x = 5
Addition subtraction elimination method;
Convert the original to 3x (x + y) = 7X3
The three formulas 3x + 3Y = 21 are obtained
If you subtract three from two, you get 2x = 10 and x = 5
Y = 2 is obtained by substituting
The same point: the equations are simplified as one variable linear equations, and the results are substituted into the equations to get the solution
Simplify the equations

Given that the vectors AB are two nonzero vectors, then in the following four conditions, the condition that can make AB collinear is
① 2a-3b = 4E, and a + 2B = - 3E
② There are different real numbers in, μ, such that in * a + μ B = 0
③ X * a + y * b = 0 (real number x, y satisfies x + y = 0)
④ If the quadrilateral ABCD is trapezoid, then the vector AB and the vector CD are collinear
Abe are vectors. You should know how to help with the analysis··

① 2a-3b = 4E, and a + 2B = - 3E
So a = - 3e-2b, so - 6e-4b-3b = 4E, so - 7b = 10e, so B = - 10e / 7, so B and E are collinear, so a = - 3E - + 20E / 7 = - E / 7, so a and E are collinear, so a and B are collinear, OK
② There are different real numbers in, μ, such that in * a + μ B = 0
Let input! = 0, so a = - μ B / input, so a and B are collinear, OK
③ X * a + y * b = 0 (real number x, y satisfies x + y = 0)
Let x = 0, so y = 0, so do not know whether a and B are collinear;
Let X! = 0, so a = - y * B / x = B, so a and B are collinear;
④ If the quadrilateral ABCD is trapezoid, then the vector AB and the vector CD are collinear
Parallel, so the same direction, so collinear

In △ ABC, BD and CD divide ∠ ABC and ∠ ACB equally. Try to explain ∠ d = 90 ° + 1 / 2 ∠ a

∠ABC+∠ACB+∠A=180 (1)
∠DBC+∠DCB+∠D=180 (2)
∠ABC=2*∠DBC
∠ACB=2*∠BCD
From (1) ∠ a = 180 - ∠ ABC - ∠ ACB = 180-2 * ∠ dbc-2 * ∠ BCD
From (2) 2 * d = 360-2 * dbc-2 * DCB = 360 - (180 - a) = 180 - A (3)
Divide both sides by two
∠D=90°+1/2∠A