1. Rút gọn biểu thức 2 5 a 3 3 a 1 a 2 a 8 A a 2 a 2 a 4 − + + + = + − − + − với a 0,a 4   . 2. Giải hệ phương trình sau: 2 5 3 2 6 x y x y  − =  − + = − 3. Cho phương trình 2 2 x m x m − + + = 2( 2) 0 −4 ( x là ẩn, m là tham số) (1). a. Giải phương trình (1) với m = −1 b. Tìm m để phương trình (1) có hai nghiệm phân biệt 1 2 x x, cùng dương thỏa mãn 1 2 2 1 8 x x x x − = .

Given this information, which expression must represent the value of b?

Tyler reads 2/5 of a book on monday, 1/3 of it on tuesday, 2/9 of it on wednesday, and 3/4 of the remainder on thursday. if he still has 14 pages left to read on friday, how many pages are there in the book?

Two researchers are attempting to create a new psychotherapy protocol that more reduces panic attacks. they believe that they have succeeded and are now in the clinical trial period of their protocol's development. they are working with several cohort groups, some of which have been through the new protocol, while others have done the standard protocol currently recommended. if these researchers are interested in evaluating the difference in the percentage of test subjects who successfully decreased their panic attacks in 2 months on the new protocol versus the percentage of test subjects who successfully decreased their panic attacks in 2 months with the traditional protocol, which of the following statistical tests would be most appropriate? a. analysis of variance (anova) b. correlation c. chi-square test d. paired t-test e. independent t-test