(a) What is wrong with the following equation? x2 + x − 42 x − 6 = x + 7 (x − 6)(x + 7) ≠ x2 + x − 42 The left-hand side is not defined for x = 0, but the right-hand side is. The left-hand side is not defined for x = 6, but the right-hand side is. None of these — the equation is correct. (b) In view of part (a), explain why the equation lim x → 6 x2 + x − 42 x − 6 = lim x → 6 (x + 7) is correct. Since x2 + x − 42 x − 6 and x + 7 are both continuous, the equation follows. Since the equation holds for all x ≠ 6, it follows that both sides of the equation approach the same limit as x → 6. This equation follows from the fact that the equation in part (a) is correct. None of these — the equation is not correct.