Problem:
Find the 3 smallest positive x-intercepts of the graph of
y=cos(12x)+cos(16x)
and list them in increasing order.
Enter your answer as a list of x-coordinates from least to greatest.
The intercepts are pi/14, pi/7, 3*pi/14.
This should help:
Use the identity
Then,
Smallest will be when m = 0, then x = pi/28, etc.
+13 
