ECON 715 Midterm: ECON715 Midterm1Fall2017solution
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Instructions: one double-sided sheet with any content is allowed, calculators are not allowed, show all the calculations, and explain your steps, if you need more space, use the back of the page, fully label all graphs. 0 1 (cid:21) c d (cid:21) , b = (cid:20) 1 0 (a) calculate the matrix product ab. Ab = (cid:20) a b c d (cid:21)(cid:20) 1 0 c d (cid:21) 0 1 (cid:21) = (cid:20) a b (b) calculate the matrix product ba. 0 1 (cid:21)(cid:20) a b c d (cid:21) c d (cid:21) = (cid:20) a b. Circle all the correct statements about a: (a) a is square matrix. (b) a is invertible. (c) a is singular. (d) a is symmetric. (e) a is idempotent: (5 points). Circle all the correct statements: (a) the matrix product ab 0 has dimension 3 (cid:2) 7. (b) the matrix product a0b has dimension 5 (cid:2) 7. (c) the matrix product b.
