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AP EAMCET · Maths · Differential Equations

If the general solution of the differential equation \(\cos ^2 x \frac{d y}{d x}+y=\tan x\) is \(y=\tan x-1+C e^{-\tan x}\) satisfies \(y\left(\frac{\pi}{4}\right)=1\), then \(C=\)

  1. A e
  2. B \(1\)
  3. C \(-1\)
  4. D \(\frac{1}{e}\)
Verified Solution

Answer & Solution

Correct Answer

(A) e

Step-by-step Solution

Detailed explanation

Given, \(\cos ^2 x \frac{d y}{d x}+y=\tan x\) \(\Rightarrow \frac{d y}{d x}+y \sec ^2 x=\tan x \cdot \sec ^2 x\)...(i) Here, \(p=\sec ^2 x\) \(\Rightarrow \quad \int p d p=\int \sec ^2 x d x=\tan x\) \(I F=e^{\tan x}\) Multiplying Eq. (i) by \(I F\), we get…