Pleasee help me! im stuck on this

Factor the following expression. 27y3 – 343 a. (3y + 7)(9y2 + 2ly + 49) b. (3y – 7)(9y2 + 2ly + 49) c. (3y – 7)(932 – 217 + 49) d. (3y + 7)(92 – 2ly + 49)

Use mathematical induction to prove the statement is true for all positive integers n, or show why it is false. 1^2 + 4^2 + 7^2 + + (3n - 2)^2 = [n(6n^2-3n-1)/2]

The domain of the following relation: r: {(3, 5), (8, 6), (2, 1), (8, 6)} is (1 point) no domain exists {1, 5, 6} {3, 8, 2, 8} {2, 3, 8}