Answer:
Explanation:
I believe that what you want to do here is to "differentiate" cos (2x - 1).
We must use the rule for differentiating cos x and also the chain rule, since the input to cos x here is (2x - 1).
(d/dx) is the derivative operator.
(d/dx) (cos x) = -sin x
(d/dx) cos (2x - 1) = - sin (2x - 1) * (d/dx) (2x -1) = -sin (2x - 1)(2) = -2sin (2x - 1)