Problem 1 Problem 1 Hi, i need to derive this and unable to fifure this out. Can anyone help me out.

[FONT=&quot]Use calculus to prove that if the present value of a cash flow is represented by: PV = cash flow ◊ exp(-rtt) and for all t’s, rtshifts up by a constant δ, the derivative of the percentage change in the bond’s price with respect to δ equals the negative of present value duration; i.e., present value duration =-(1/P)(∂P/∂δ)