Question

Range of function f(x) = 3cos2x is (a) [-3,3] (b) (-1,1) (c) R (d) [-1/2,1/2] ​

Answer 1

Answer:

the value of cosθ always lies between -1 and 1

so, θ = 2x

-1 ≤ cos2x ≤ 1

multiplying by 3

-3 ≤ 3cos2x ≤ 3

-3 ≤ y  ≤ 3

range = [ -3,3 ]

Step-by-step explanation: