Consider the non-constant differentiable func | vedclass

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(A) Given the functional equation $\frac{f(x)}{f(y)}=f(x-y)$.Setting $y=0$,we get $\frac{f(x)}{f(0)}=f(x)$,which implies $f(0)=1$.Differentiating both

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$\frac{p^{2}}{q}$

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(A) Given the functional equation $\frac{f(x)}{f(y)}=f(x-y)$.Setting $y=0$,we get $\frac{f(x)}{f(0)}=f(x)$,which implies $f(0)=1$.Differentiating both sides with respect to $x$,we get $\frac{f^{\prime}(x)}{f(y)}=f^{\prime}(x-y)$.Setting $x=0$,we have $\frac{f^{\prime}(0)}{f(y)}=f^{\prime}(-y)$.Since $f^{\prime}(0)=p$,we get $f^{\prime}(-y) = \frac{p}{f(y)}$.Also,differentiating the original equation with respect to $y$,we get $f(x) \cdot (-\frac{f^{\prime}(y)}{(f(y))^2}) = f^{\prime}(x-y) \cdot (-1)$.This simplifies to $\frac{f(x) f^{\prime}(y)}{(f(y))^2} = f^{\prime}(x-y)$.At $y=0$,$\frac{f(x) f^{\prime}(0)}{(f(0))^2} = f^{\prime}(x)$,so $f^{\prime}(x) = p f(x)$.This is a linear differential equation with solution $f(x) = e^{px}$.Then $f^{\prime}(x) = p e^{px}$.Given $f^{\prime}(5) = q$,we have $p e^{5p} = q$,so $e^{5p} = \frac{q}{p}$.We need $f^{\prime}(-5) = p e^{-5p} = \frac{p}{e^{5p}} = \frac{p}{q/p} = \frac{p^2}{q}$.

Consider the non-constant differentiable function $f$ of one variable which obeys the relation $\frac{f(x)}{f(y)}=f(x-y)$. If $f^{\prime}(0)=p$ and $f^{\prime}(5)=q$,then $f^{\prime}(-5)$ is

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