Câu 1 (2 điểm). Cho hệ các vector U ={(1,2,8 );(0,-1,-7); (2,3, 9);(1,0,-6) } . a. Tìm số chiều và một cơ sở W của không gian con sinh bởi hệ vector U .
b. Tìm tham số k để u=(2,3, k2+1) là một tổ hợp tuyến tính của W , và suy ra [u ]W .

Determine if the equation defines y as a function of x: 2xy = 1. yes o no

The length of the shadow of a building is 120 meters, as shown below: building shadow 120 m what is the height of the building? (1 point)

Amanufacturing firm has been averaging 16.8 orders per week for several years. however, during a recession, orders appeared to slow. suppose the firm’s production manager randomly samples 31 weeks and finds an average of 15.6 orders with a standard deviation of 2.3 orders. using a 0.025 significance level, test whether the mean number of orders has decreased. type the full 5 step procedure into the answer box, then for multiple choice practice, answer the following: 1. what is the name and symbol of the parameter that you are testing? 2. what is the symbol and value of the point estimate of that parameter? 3. what distribution are you using to test this parameter? 4. what is the critical value? 5. what is the test statistic value? 6. what is the p-value?