If y=500e7x+600e−7x, show that d2ydx2=49 y.
Given, y=500e7x+600e−7x .......(i)
Differentiating twicely w.r.t. x, we get
dydx=500e7xddx(7x)+600e−7xddx(−7x)=500e7x.7+600e−7x.(−7)and d2ydx2=(7×500)e7x.7−(7×600)e−7x(−7)=49{500e7x+600e−7x}⇒ d2ydx2=49 y. Hence proved.