If ∫π‘₯^3 sin^4 (π‘₯^4 )cos(π‘₯^4 )𝑑π‘₯=π‘Žsin^5 (π‘₯^4 )+C, then π‘Ž is - CBSE Class 12 Sample Paper for 2026 Boards

part 2 - Question 12 - CBSE Class 12 Sample Paper for 2026 Boards - Solutions of Sample Papers and Past Year Papers - for Class 12 Boards - Class 12

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Question 12 If ∫π‘₯^3 sin^4 (π‘₯^4 )cos(π‘₯^4 )𝑑π‘₯=π‘Žsin^5 (π‘₯^4 )+C, then π‘Ž is equal to (A) βˆ’1/10 (B) 1/20 (C) 1/4 (D) 1/5Finding ∫π‘₯^3 sin^4 (π‘₯^4 )cos(π‘₯^4 )𝑑π‘₯ Let 𝐭=𝐬𝐒𝐧⁑(𝒙^πŸ’ ) Differentiating t 𝒅𝒕/𝒅𝒙=〖𝒄𝒐𝒔 〗⁑(𝒙^πŸ’ ) Γ— (𝒙^πŸ’ )^β€² 𝑑𝑑/𝑑π‘₯=γ€–π‘π‘œπ‘  〗⁑(π‘₯^4 ) Γ— 4π‘₯^3 𝑑𝑑=γ€–π‘π‘œπ‘  〗⁑(π‘₯^4 )4π‘₯^3 𝑑π‘₯ 𝒅𝒕/πŸ’=〖𝒄𝒐𝒔 〗⁑(𝒙^πŸ’ ) 𝒙^πŸ‘ 𝒅𝒙 Now, ∫π‘₯^3 sin^4 (π‘₯^4 )cos(π‘₯^4 )𝑑π‘₯=∫1β–’(𝒕^πŸ’ 𝒅𝒕)/πŸ’ =1/4 ∫1▒〖𝑑^4 𝑑𝑑〗 =1/4 ×𝑑^5/5+𝐢 =𝟏/𝟐𝟎 𝒕^πŸ“+𝐢 Putting back 𝑑=𝑠𝑖𝑛⁑(π‘₯^4 ) =𝟏/𝟐𝟎 γ€–π’”π’Šπ’γ€—^πŸ“ (𝒙^πŸ’ ) +π‘ͺ Comparing with π’‚γ€–π’”π’Šπ’γ€—^πŸ“ (𝒙^πŸ’ )+𝐂, then π‘Ž is equal to 𝟏/𝟐𝟎 So, the correct answer is (B)

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