A Concrete Noun is a word that signifies something that can be seen, heard and touched in the real world. For example; table, lamp, desk, and pen, are all concrete nouns.
We use the quotient rule to find dy/dt. Let u = 4t and v = (t^2 + 5). Then, u' = 4 and v' = 2t. Hence,
dy/dt = u'v - v'u / v2 = 4(t^2 + 5) - 4t x 2t / (t^2 + 5)2 = 20 - 4t