The teacher made a strict criticism on me and changed the wrong sentence

Strict to severe

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1. Matrix A = first line 4 1, second line 1 4 1, third line 1 1 4 1. Find the orthogonal matrix C so that C ^ TAC is diagonal 2. Write the quadratic form f corresponding to a 3. Write the standard form of F
2. Question: some students of grade 6 go boating. If 5 people sit on each boat, 14 people have no boat to take. If 7 people sit on each boat, one boat can take 4 people How many students go boating in sixth grade?
3. When k is a value, the function f (x) has continuity in its domain f（x）=sinx/x x=0
4. How to say this in English
5. X / 1 * 2 + X / 2 * 3 + X / 3 * 4 +... + X / 99 * 100 = 1 Is the final x = 100 / 99
6. Explain an English word oft-predicted
7. Is displacement a vector or a scalar?
8. Is time a scalar or a vector
9. Does time have a direction, a vector or a scalar?
10. Is momentum a vector or a scalar?
11. How to transform rectangular coordinate velocity into polar coordinate velocity In a three-dimensional velocity field, it is necessary to decompose the velocity on a circular surface into radial velocity and tangential velocity We know how to use the dot product of vector to get the radial velocity, but we don't know how to get the tangential velocity. Because velocity has direction, we can't simply use Pythagorean theorem to get the tangential velocity Can you explain in detail how to find the tangent vector of the next derivative
12. The function of vector in Physics
13. Given the vector a = (E, 2), B = (- 3, 5), and the angle between a and B is obtuse, what is the value range of E,
14. Given the vector a = (a, 2), B = (- 3, 5), and the angle between vector a and vector B is obtuse angle, the value range of a is obtained Given the vector a = (in, - 2), B = (- 3,5), and the angle between a and B is obtuse, then the value range of in
15. Given that vector a = (2, x), vector b = (3, 4), and the angle between vector a and vector B is obtuse, then the value range of X is___ A.x>-2/3 B. X > - 2 / 3 and X ≠ 8 / 3 C. X2 / 3 and X ≠ 8 / 3
16. Given that a = (x, 2), B = (- 3, 5), and the angle between a and B is obtuse, then the value range of X is? Letter A. B is vector!
17. Given the vectors a = (x, 2) and B = (- 3, - 5), the angle between a and B is obtuse angle, find the value range of X
18. Vector a (m, 2m), vector b (- - 3M, 2) if the angle between vector a and vector B is an obtuse angle, how can we solve the problem of the value range of M?
19. If the angle between vector a = (3, m, 4) and B = (- 2, 2, m) is obtuse, then the value range of M, please write the detailed process, the answer is m
20. If a = (1,2), B = (- 1,0), C = (4,6) are given, and a and B are used to represent C, what is C