Passage

Directions: Given below are two series I and II. Each series contains a wrong term, and both follow different patterns. Solve the series and answer the following question. Series I: x, y + 3, z + 8, 63, 268, 1365, 8226 Series II: 2y - 1, 2z - 2, 36, 10x + 2, 98, 147, 209 Note: (i) 5ym 2 - (21 - x)m + 3 = 0, roots of equation are and . (where < ) (ii) any multiple of b give a number with unit digit zero. (iii) z - a = 7 and LCM of a and 7 is 21.

What is the difference between the wrong term in Series II and the wrong term in Series I?