How to Evaluate the Integral in the PDE Solution for U(x,t)?

moo5003
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Homework Statement



U is a function of x and t

d/dt(U) = d/dx(U) + V(x,t)U
U(x,0) = f(x)

Suppose:
U(x,t) = e^(Integral from 0 to 1 [V(x+s,t-s)]ds) * f(x+t)

Show directly (no change of variables) that this solves the above PDE
Show using change of variables that this solves the above PDE letting
Alpha = x+t
Gamma = x-t

The Attempt at a Solution



My main question is how to evlauate d/dt { Integral from 0 to 1 [V(x+s,t-s)]ds }
 
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Use the Liebniz integral rule, described in these articles at http://en.wikipedia.org/wiki/Leibniz_integral_rule" .
 
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There are two things I don't understand about this problem. First, when finding the nth root of a number, there should in theory be n solutions. However, the formula produces n+1 roots. Here is how. The first root is simply ##\left(r\right)^{\left(\frac{1}{n}\right)}##. Then you multiply this first root by n additional expressions given by the formula, as you go through k=0,1,...n-1. So you end up with n+1 roots, which cannot be correct. Let me illustrate what I mean. For this...
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