Integration by Substitution. The rate of growth of Grass carp, one of the most common type of fish, was modelled by the equation where t is measured in years and t} in kilograms per year. Consider the integral 4 3x+12 dx 2 x2+8x+2 After substitution into u, the new integral can be written I) finial all {a} The value ofA is 012 03 03x+4 01.5 03x Ox+4 OX 00 (b) The upper limit of integration b is O 100 O 22 O 4 O 2 O 50 O 44 O 22 O 50