Math 0420 – Practice Test – Sequences, Limits, and Continuity
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Math 0420 – Practice Test – Sequences, Limits, and Continuity
1. (a) Find a value of δ > 0 such that when |x - 4| < δ , |x2 - 16| < 1/2. (b) Show that x(l) cos ╱ ← does not exist.
2. Find all values of c such that the following function is continuous on R. Justify your claims.
-x if x s 0
f (x) = . cx cos (1/x) if 0 < x s 2/π
│ x + c if x > 2/π .
3. Let {xn } and {yn } be sequences such that:
(i) Each yn > 0
(ii) lim yn = 0
(iii) |xm - xn | s yn for all m > n.
Show that {xn } is a convergent sequence.
4. (a) Show, by definition, that f (x) = x2 + x is uniformly continuous on (0, 10).
(b) Show that f (x) = 1/x2 is not uniformly continuous on (0, 10).
5. Show that x = 2 tan x - 1 has a solution in the interval (0, π/4).
2023-02-07