1. a 4, 10, 16, 22, 28,... a. Find the closed form: an 0 b. Use the closed form to find a 12 = a. Find the closed form: bn = b. Use the closed form to find b21 = a. Find the closed form: cn = b. Use the closed form to find C47 = 4. d= -3,-9, -15, -21, -27,... - a. Find the closed form: dn = b. Use the closed form to find d75