Drug Dosages Thomas Young has suggested the following rule for calculating the dosage of medicine for children 1 to 12 yr old. If a denotes the adult dosage (in milligrams) and if t is the child's age (in years), then the child's dosage is given by the following function. at Dt= () t+12 Suppose the adult dosage of a substance is 640 mg. Find an expression that gives the rate (in mg/year) of change of a child's dosage with respect to the child's age. 0'03) = What is the rate of change (in mg/year) of a child's dosage with respect to his or her age for a 1-yr-old child? A 10-yr-old child? (Round your answers to three decimal places.) 1-yr-old x mg/year 10-yr-old x mg/year Find an equation of the tangent line to the graph of the following function fat the specified point. f(x) = (x3 + 3)(3x2 4x + 2); (1, 4). S