When seeking the value of X, the value of the algebraic formula 2x + 9 / x + 3 - (1 / x-3) - 2 / X is equal to 2. Can you understand what I mean What if the answer helps

When seeking the value of X, the value of the algebraic formula 2x + 9 / x + 3 - (1 / x-3) - 2 / X is equal to 2. Can you understand what I mean What if the answer helps

2x+9/x+3 - (1/x-3)- 2/x=2x(x-3)（2x+9）-x(x+3)-2(x+3)(x-3)=2x(x+3)(x-3)x(2x²+3x-27)-x²-3x-2x²+18=2x³-18x2x³+3x²-27x-3x²-3x+18=2x²-18x-30x+18=-18x12x=18x=1.5

The square of 2 (2x + 1) - 3 = 0
Quadratic equation of one variable

The square of 2 (2x + 1) - 3 = 0
Square of (2x + 1) = 3 / 2
2x+1=±√6/2
2x=-1±√6/2
therefore
x1,2=(-2±√6)/4

A rectangular classroom measured on a 1:500 scale plan is 3cm long and 2cm wide. The actual floor area of the classroom is square meters

15x10 = 150 (M2)
The actual floor area of this classroom is 150 square meters

Mathematician story, short
About 100 words

Su Buqing, a mathematician, was born in a mountain village in Pingyang County, Zhejiang Province in September 1902. Although his family was poor, his parents spared no effort to help him go to school

There's a quadrangular meadow ABCD,

Connect AC,
∠ B=90°,AB=4m,BC=3m
According to Pythagorean theorem, AC = √ (4 ^ 2 + 3 ^ 2) = 5m
Because CD = 12M, Da = 13m
So AC ^ 2 + CD ^ 2 = ad ^ 2
Triangle ACD is right triangle, ∠ ACD = 90 degree
So s quadrilateral = s △ ABC + s △ ACD
=4*3/2+12*5/2
=36 square meters
Therefore, the area of the quadrangle grassland is 36 square meters

Take the elevator is to do translation movement
Ha ha, the standard answer is:
I can't figure it out for the kids,

The movement of the elevator is indeed translational movement, but the concept of translational movement is not touched by the third grade of primary school, so I think the teacher's original intention may be to let the children judge whether the elevator is doing horizontal movement, which is right or wrong, and the two concepts of translational movement and horizontal movement are not confused, so it is written as translational movement
So I think the teacher must give a reasonable explanation for this problem. If the teacher is wrong, the teacher should admit it. If the teacher has his own ideas, he can also talk about it together. He can't let the child have a wrong concept, which is not very good for the growth of children's knowledge
The teacher should also discuss his own ideas. Of course, one of the above respondents said it better, "take the elevator, people take the elevator". In fact, the action is static relative to the elevator, and the elevator itself is moving. However, it seems far fetched to say that. The math problem of grade three in primary school looks a bit literal, And the third grade of primary school is not relatively static

Given that the angle between vectors a and B is 45 degrees, then the angle between - 2A and 3b is 45 degrees

135 degrees

As shown in the figure, △ ABC is an equilateral triangle, points D, e and F are on the sides of AB, BC and Ca respectively, and △ DEF is an equilateral triangle. Proof: △ ADF ≌ △ CFE

It is proved that: ∵ ABC is an equilateral triangle, ∵ a = ∵ C = 60 °. ∵ ADF + ∵ AFD = 120 ° (2 points) ∵ DEF is an equilateral triangle, ∵ DFE = 60 °, DF = EF. ∵ AFD + ∵ CFE = 120 °. ∵ ADF =