Using the method of Example 2.2i, prove that the following limits exist.
a) 2 - 1/n → 2 as n → ∞.
b) 1 + π/√n → 1 as n → ∞.
c) 3(1 + 1/n) → 3 as n → ∞.
d) (2n2 + l)/(3n2) → 2/3 as n → ∞.