Show that the following equations have at least one solution in the given intervals.
a. x cos x − 2x2 + 3x − 1 = 0, [0.2, 0.3] and [1.2, 1.3]
b. (x − 2)2 − ln x = 0, [1, 2] and [e, 4]
c. 2x cos (2x) − (x − 2)2 = 0, [2, 3] and [3, 4]
d. x − (ln x)x = 0, [4, 5]