What is the first part of the second step to prove that Sn 1 + 4 + 7 + ... + (3n - 2) = n(3n-1)/2? a. Verify that Sn is valid for n = 1 c. Assume that Sn is valid for n = k b. Show that Sn is valid for n = k d. Prove that Sn is valid for n = k + 1

Add, subtract, multiply, or divide as indicated. list any restrictions for the variable(s) and simplify the answers when possible. 1) x-2 / x+5 + 3x / 2x-1 2) x+6 / x-6 - x^2 / x+6 3) x+9 / x-4 + x+2 / x^2-11x+28 4) x / x^2-64 + 11 / 2x^2+11x-40 5) 5 / x + 11 / x-3 - x-4 / x^2+2x-15