Answer:
f(x) = 0 when
x = (k/3 + 1/4)pi for all k integer
Step-by-step explanation:
If you are looking for the roots of f(x), i.e. roots of f(x)=0, then
f(x) = -2cos(3x-pi/4) = 0
divide by -2
cos(3x-pi/4) = 0
Since cos((k+1/2)pi) = 0 for all integer values of k,
we equate
3x-pi/4 = (k+1/2)pi
3x = (k+1/2)pi + pi/4
3x = (k+ 3/4) pi
x = (k/3 + 1/4)pi for all k integer
Otherwise, please complete or edit the question.
