Find the magnitude of the trig term by taking the absolute value of the coefficient.

The lower bound of the range for cosine is found by substituting the negative magnitude of the coefficient into the equation.

The upper bound of the range for cosine is found by substituting the positive magnitude of the coefficient into the equation.

The range is .

Interval Notation:

Set-Builder Notation:

Find the Range f(x)=-4cos(2x)