Misc 15 (MCQ) - General solution: ex dy + (y ex + 2x) dx = 0 - Miscellaneous

part 2 - Misc 15 (MCQ) - Miscellaneous - Serial order wise - Chapter 9 Class 12 Differential Equations
part 3 - Misc 15 (MCQ) - Miscellaneous - Serial order wise - Chapter 9 Class 12 Differential Equations

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Misc 15 The general solution of the differential equation 𝑒^π‘₯ 𝑑𝑦+(𝑦 𝑒^π‘₯+2π‘₯)𝑑π‘₯=0 is (A) π‘₯ 𝑒^𝑦+π‘₯^2=𝐢 (B) π‘₯ 𝑒^𝑦+𝑦^2=𝐢 (C) 𝑦 𝑒^π‘₯+π‘₯^2=𝐢 (D) 𝑦 𝑒^𝑦+π‘₯^2=𝐢 Given equation 𝑒^π‘₯ 𝑑𝑦+(𝑦 𝑒^π‘₯+2π‘₯)𝑑π‘₯=0 𝒆^𝒙 π’…π’š=βˆ’(π’š 𝒆^𝒙+πŸπ’™)𝒅𝒙 𝑑𝑦/𝑑π‘₯= (βˆ’(𝑦𝑒^π‘₯ + 2π‘₯))/𝑒^π‘₯ 𝑑𝑦/𝑑π‘₯ = (βˆ’π‘¦π‘’^π‘₯)/𝑒^π‘₯ βˆ’2π‘₯/𝑒^π‘₯ 𝑑𝑦/𝑑π‘₯ = βˆ’π‘¦βˆ’2π‘₯/𝑒^π‘₯ π’…π’š/𝒅𝒙 + y = (βˆ’πŸπ’™)/𝒆^𝒙 Differential equation is of the form 𝑑𝑦/𝑑π‘₯ + Py = Q where P = 1 & Q = (βˆ’πŸπ’™)/𝒆^𝒙 Now, IF = 𝑒^∫1▒〖𝑃 𝑑π‘₯γ€— IF = 𝑒^∫1β–’γ€–1 𝑑π‘₯γ€— IF = 𝒆^𝒙 Solution is y(IF) = ∫1β–’γ€–(𝑄×𝐼𝐹)𝑑π‘₯+𝑐〗 yex = ∫1β–’γ€–(βˆ’πŸπ’™)/𝒆^𝒙 𝒆^𝒙 𝒅𝒙+𝒄〗 yex = βˆ’βˆ«1β–’γ€–2π‘₯ 𝑑π‘₯+𝑐〗 yex = βˆ’2Γ—π‘₯^2/2+𝑐 yex = βˆ’π‘₯^2+𝑐 yex + 𝒙^𝟐=𝒄 So, the correct answer is (c)

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