Problem 2.15. Compute the following sum and justify every step: n7+1 [ 3(k+ 2)2 +. 5-4k+1 + 74k-10 116-7k k=n2 Problem 2.16. Compute the following sum (in terms of n, ): B 1 K=A k(k + 1) (k + 2) (k +3)(k+4) (k+5) Problem 2.17. Compute the following sum. Justify every step: n? 3[1 1 cos(733*+2)] _ 3/11 cos(732*+20)| K=n Problem 2.18. Compute the following sum. Justify every step: 2400 72-70j + 951j-1 8-32j-2 j=100 Problem 2.19. Use translation invariance to fully justify and express B in terms of k so that 2n7+10 2n7-11 k=n6 k=n'-21 Problem 2.20. (The Glossary: Definitions and Theorems) State precisely the following definitions and theorems. (1) The Linearity Property for sums. (2) The Telescoping Property for sums. (3) The Geometric Property for sums. (4) The Associativity Property for sums. (5) 2k-1 (6) (7)