Example 7 - Chapter 7 Class 12 Integrals - Part 7

Example 7 - Chapter 7 Class 12 Integrals - Part 8
Example 7 - Chapter 7 Class 12 Integrals - Part 9


Transcript

Example 7 Find (iii) ∫1β–’sin^3⁑π‘₯ 𝑑π‘₯ We know that 𝑠𝑖𝑛 3π‘₯=3 𝑠𝑖𝑛⁑π‘₯βˆ’4 〖𝑠𝑖𝑛〗^3⁑π‘₯ 4 〖𝑠𝑖𝑛〗^3 π‘₯=3 𝑠𝑖𝑛⁑π‘₯βˆ’π‘ π‘–π‘›β‘3π‘₯ 〖𝑠𝑖𝑛〗^3 π‘₯=(3 𝑠𝑖𝑛⁑π‘₯ βˆ’ 𝑠𝑖𝑛⁑3π‘₯)/4 ∫1β–’sin^3⁑π‘₯ 𝑑π‘₯=∫1β–’(3 sin⁑π‘₯ βˆ’ sin⁑3π‘₯)/4 𝑑π‘₯ =1/4 ∫1β–’(3 sin⁑π‘₯βˆ’sin⁑3π‘₯ ) 𝑑π‘₯ =1/4 [3∫1β–’sin⁑π‘₯ 𝑑π‘₯βˆ’βˆ«1β–’sin⁑3π‘₯ 𝑑π‘₯] ∫1β–’π’”π’Šπ’β‘πŸ‘π’™ 𝒅𝒙 Let 3π‘₯=𝑑 3=𝑑𝑑/𝑑π‘₯ 𝑑π‘₯=1/3 𝑑𝑑 ∫1β–’π’”π’Šπ’β‘πŸ‘π’™ 𝒅𝒙=∫1β–’sin⁑𝑑 . 1/3 𝑑𝑑 =1/3 ∫1β–’sin⁑𝑑 . 𝑑𝑑 =1/3 (γ€–βˆ’cos〗⁑𝑑+𝐢1) =βˆ’1/3 cos⁑𝑑+1/3 𝐢1 Putting value of 𝑑 =βˆ’1/3 cos⁑3π‘₯+1/3 𝐢1 ∫1β–’π’”π’Šπ’β‘π’™ 𝒅𝒙 =βˆ’cos⁑π‘₯+𝐢2 Thus, ∫1β–’sin^3⁑π‘₯ 𝑑π‘₯=1/4 [3∫1β–’γ€–sin⁑π‘₯ 𝑑π‘₯γ€—βˆ’βˆ«1β–’sin⁑3π‘₯ 𝑑π‘₯] =1/4 [3(βˆ’cos⁑π‘₯+𝐢2)βˆ’(βˆ’1/3 cos⁑3π‘₯+1/3 𝐢1)] =1/4 [βˆ’3 cos⁑π‘₯+3 𝐢2+ 1/3 cos⁑3π‘₯+1/3 𝐢1] =1/4 [βˆ’3 cos⁑π‘₯+1/3 cos⁑3π‘₯+(3 𝐢2βˆ’1/3 𝐢1)] =(βˆ’3)/4 cos⁑π‘₯+1/12 cos⁑3π‘₯+1/4 (3 𝐢2βˆ’1/3 𝐢1) =(βˆ’πŸ‘)/πŸ’ 𝒄𝒐𝒔⁑𝒙+𝟏/𝟏𝟐 π’„π’π’”β‘πŸ‘π’™+π‘ͺ ("As" 1/4 (3 𝐢2βˆ’1/3 𝐢1)=𝐢)

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Davneet Singh

Davneet Singh has done his B.Tech from Indian Institute of Technology, Kanpur. He has been teaching from the past 14 years. He provides courses for Maths, Science, Social Science, Physics, Chemistry, Computer Science at Teachoo.