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【段考】高二英文
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111年 - 1102第一次期中考英二英文Lesson 5#110235
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(c) (2%) Find, where C is the straight line going from the points (2,2,1) to the point (1,-1,2).
#471987
1. (15%) Evaluate the following integral
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(a) (7%) Compute the quantity A given below where the Fourier transform of f1(t) is given in the following figure (a).
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(b) (8%) Compute the quantity B given below where the Fourier transform of f2(t) is given in the following figure (b).
#471990
(a) (6%) Please continue the argument to derive the result rank(A) = rank(R). .
#471991
接下來前段是背景知識介紹,之後才是提問)In solving the linear equation Ax=b for a igiven , instead of using the elemnentary row operations (i.e. the Gauss eliminations) to manipulate the equation, we may also apply the QR factorization to the equation to get QRx = b, which implies further QTQRx = QTb. Since QTQ = In, it gives Rx = QTb. Thus, according to the result of(a), when all columns of A are linearly independent, the square matrix R is nonsingular and so the solution x =b is obtained. It seems that we may summarize the above argument as the following statement:Given , where all columns of A are assumed linearly independent, then solution to the equation Ax = o can always be computed from x = , where Q and R are matrices obtained from the @R factorization of A. However, the simple example shows that the summary is incorrect because, according to the summary, the solution is x= and obviously it does not satisfy the original equation. (b) (5%) What is the error (or are the errors) in the argument right before the summary to make it incorrect?
#471992