Cut a line from matrix A to get matrix B. ask the relation between the rank of a and B,

Cut a line from matrix A to get matrix B. ask the relation between the rank of a and B,

I think it's complicated. I think we should solve it from the angle of the value of adjoint matrix and determinant

Is it possible to judge the rank by the number of non-zero rows by transforming the matrix into a row ladder type matrix? Do you need to transform it into the simplest type?

The matrix is transformed into row ladder type, and its non-zero row number is the rank of the matrix
The row simplest form is usually used to find the solution of a system of linear equations or to express a vector as a linear combination of other vectors

As shown in the figure, in RT △ ABC, ∠ ACB = 90 °, D is the midpoint of AB, AE ‖ CD, CE ‖ AB, judge the shape of quadrilateral adce, and prove your conclusion

The reason is as follows: ∵ AE ∥ CD, CE ∥ AB, ∵ quadrilateral adce is parallelogram. In RT △ ABC, ∵ ACB = 90 °, D is the midpoint of AB, ∵ CD = ad, ∵ quadrilateral adce is diamond

Is 5y-9 = 1 / 2Y a linear equation with one variable? If an equation contains multiple identical unknowns (for example, x), and the degree is 1, is it a linear equation with one variable

5y-9 = 1 / 2Y is a linear equation with one variable
Calculate the equation of degree one variable

Given a (2,3), B (5,4), C (7,10), vector AP = vector AB + λ vector AC, ① if point P is on the bisector of the first and third quadrant angles, find λ
② If the distance from point P to the two coordinate axes is equal, calculate λ

AB = (3,1), AC = (5,7), let P (x, y) AP = AB + λ AC, that is, X-2 = 3 + 5 λ Y-3 = 1 + 7 λ, then x = 5 + 5 λ y = 4 + 7 λ (1) P is on the angular bisector of a three quadrant, then y = - X5 + 5 λ = - (4 + 7 λ) = - 4-7 λ, so the distance from λ = - 3 / 4 (2) P to the two coordinate axis is equal, then | x | = | y | 5 + 5 λ | = | 4 + 7 λ | that is, 5 + 5 λ = 4 + 7 λ

As shown in the figure, ad is the middle line of △ ABC, de ‖ AB, and de = AB, connecting AE and EC

It is proved that: if ∵ de ∥ AB, and de = AB, ∥ a quadrilateral ABDE is a parallelogram, ∥ BD = AE, AE ∥ BC, ad is the middle line of △ ABC, ∥ CD = BD = AE, ∥ a quadrilateral adce is a parallelogram, ∥ AC and ED are equally divided

The difference between a times the square of X and the square of Y is 2XY. Then subtract the difference between B times the square of X and the square of Y. solve the problem by factorization
A (x * + 2XY + y *) - B (x * - y *) uses factorization to solve this problem, * denotes square

a(X*+2XY+Y*)-b(X*-Y*)
=a(x+y)^2-b(x+y)(x-y)
=(x+y)[a(x+y)-b(x-y)]
=(x+y)[(a-b)x+(a+b)y]

If there is a point P on the ellipse x ^ 2 / 25 + y ^ 2 / 9 = 1 whose distance from the left focus is equal to three times of the distance from the right focus, then the coordinate of P is?

1. The characteristic of ellipse is that the sum of distance to left and right focus is fixed. 2. The semimajor axis of the ellipse is 5, the semiminor axis is 3.3, the sum of distance from any point of the ellipse to the double focus is 10.4, the sum of distance from any point of the ellipse to the double focus is (4,0) and (- 4,0) on the ellipse by (0,3)

In the triangle ABC, ^ B = 60 °, CD and AE are the heights on the sides of AB and BC, respectively

Take the middle point m of AC, connect DM and EM, the middle line on the hypotenuse of right triangle is equal to half of the hypotenuse, DM = EM = am = cm, in the triangle ABC, ∠ B = 60 °, BAC + BCA = 120 °, in the isosceles triangle ADM, ∠ DMA = 180 ° - 2 ∠ dam, similarly, ∠ EMC = 180 ° - 2 ∠ ECM, ∠ DME = 180 ° - DMA - ∠ EMC = 180 °

Given that the modulus of complex z = (X-2) + Yi (x, y ∈ R) is 3, then the value range of YX is______ ．

∵ the module of complex number (X-2) + Yi (x, y ∈ R) is 3 ∵ (X-2) 2 + y2 = 3. According to the slope of YX from the moving point (x, y) to the fixed point (0, 0), we know that the maximum value of YX is 3. Similarly, the minimum value is - 3, and the value range of ∵ YX is [- 3, 3], so the answer is: [- 3, 3]