19: The conditions give (in the same order):
- This condition is already solved.
- This condition is best solved by substitution
y = ln(x), leading to a quadratic equation with
roots y = −1 and
y = 2. The inequalities
ln(x) ≠ −1 and
ln(x) ≠ 2 give
x ≠ e−1 and
x ≠ e2.
Now intersect these conditions.
Answer