# How do you find the range of y = -2 cos 3x?

Apr 25, 2015

Range [-2,2]

Cosine value varies from -1 to 1, hence -2cos 3x can vary from +2 to -2. The range of the given function , in interval notation, would thus be [-2,2]. In set builder notation it can be expressed as { yinR |-2<=y<=2 }