Q.
The integral I=∫(sin(x2)+2x2cos(x2))dx=xH(x)+C, (where C is the constant of integration). If the range of H(x) is [a,b] , then the value of a+2b is equal to
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NTA AbhyasNTA Abhyas 2020Integrals
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Answer: 1
Solution:
Given integral I=∫(1⋅sin(x2)+x⋅2xcos(x2))dx (∵∫(f′g+f⋅g′)dx=∫(fg)′dx=f⋅g+C) =x⋅sin(x2)+C ∴H(x)=sin(x2), whose range is [-1,1] ∴a=−1,b=1⇒a+2b=1