| 1. |
Find second derivative of ex = tan2y with respect to x. |
|
Answer» ex = tan 2y----(1) differentiate (1) w.r.t. x we get ex = 2 sec22y.\(\frac{dy}{dx}\)----(2) differentiate (2) w.r.t. x, we get ex = 2sec22y \(\frac{d^2y}{dx^2}+\) 8sec 2y. sec 2y tan 2y \((\frac{dy}{dx})^2\) = 2 sec22y.\(\frac{d^2y}{dx^2}+\) 8 sec22y tan 2y \((\frac{e^x}{2sec^22y})^2\) (From (2)) = 2 sec22y \(\frac{d^2y}{dx^2}+\) 2 \(\frac{tan2y}{sec^22y}e^{2x}\) ⇒ 2 sec22y.\(\frac{d^2y}{dx^2}\) = ex - \(\frac{2tan2y}{sec^22y}e^{2x}\) ⇒ 2(1 + tan22y)\(\frac{d^2y}{dx^2}\) = ex - \(\frac{2.e^x.e^{2x}}{1+tan^22y}\) (\(\because\) 1 + tan2\(\theta\) = sec2\(\theta\) and From (1)) ⇒ 2(1 + e2x) \(\frac{d^2y}{dx^2}\) = ex - \(\frac{2e^{3x}}{1+e^{2x}}\) ⇒ \(\frac{d^2y}{dx^2}\) = \(\frac{e^{3x}+e^x-2e^{3x}}{2(1+e^{2x})^2}\) |
|