MHB What is the relationship between P and G(t) in Calculus with Exponential?

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The relationship between P and G(t) in the context of calculus with exponential functions is established through the equation P = P_0 × e^(G(t)). The derivative G'(t) is given as a + bt, leading to the integral G(t) = at + (1/2)bt^2 + C. To demonstrate that G(0) = 0, it is shown that when P(0) = P_0, it follows that e^(G(0)) must equal 1, which implies G(0) = 0. This confirms the initial condition necessary for the relationship between P and G(t). Overall, the discussion highlights the importance of initial conditions in exponential growth models.
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For $$P=P_0\times e^{G(t)}$$

and $$G'(t) = a+bt$$

Show $$G(0)=0$$

I get $$G(t) = \int a+bt ~dt = at+\frac{1}{2} b t^2+C$$ therefore $$G(0)=C $$
 
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Bushy said:
For $$P=P_0\times e^{G(t)}$$

and $$G'(t) = a+bt$$

Show $$G(0)=0$$

I get $$G(t) = \int a+bt ~dt = at+\frac{1}{2} b t^2+C$$ therefore $$G(0)=C $$

Hi Bushy! ;)

I expect that it's intended that $P(0) = P_0$.

Then we have:
$$P_0 e^{G(0)} = P_0 \quad\Rightarrow\quad e^{G(0)} = 1 \quad\Rightarrow\quad G(0)=0
$$
 
There are probably loads of proofs of this online, but I do not want to cheat. Here is my attempt: Convexity says that $$f(\lambda a + (1-\lambda)b) \leq \lambda f(a) + (1-\lambda) f(b)$$ $$f(b + \lambda(a-b)) \leq f(b) + \lambda (f(a) - f(b))$$ We know from the intermediate value theorem that there exists a ##c \in (b,a)## such that $$\frac{f(a) - f(b)}{a-b} = f'(c).$$ Hence $$f(b + \lambda(a-b)) \leq f(b) + \lambda (a - b) f'(c))$$ $$\frac{f(b + \lambda(a-b)) - f(b)}{\lambda(a-b)}...

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