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(1 point) If R denotes the reaction of the body to some stimulus of strength , the \\ sensitivity S is defined to be the rate of change of the reaction with respect to @. A particular example is that when the brightness a of a light source is increased, the eye reacts by decreasing the area R of the pupil. The experimental formula 41 + 2325 R = 1 + 0.4x5 can be used to model the dependence of R on a when R is measured in square millimeters and x is measured in appropriate units of brightness. Find the sensitivity corresponding to x = 2