Question

Exercise gives a function ƒ(x) and numbers L, xo and E > 0 (E being Epsilon).
Find an open interval about xo on which the inequality |f(x) - L| < E holds. Then give a value for delta > 0 such that
for all x satisfying 0 < |x - xo| < delta
the inequality |f(x) - L|| < E
holds.

f(x) = sqrt(x-7),
L = 4,
xo = 23,
E = 1