InterviewSolution
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InterviewSolution
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The number of real solutions of the equation 2 sin 3x + sin 7x - 3 = 0 which lie in the interval `[-2pi , 2pi]` isA. 1B. 2C. 3D. 4 |
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Answer» Correct Answer - B only possible when sin 3x = 1 & sin 7x = 1 sin 3x = 1 sin3x = sin(4n+ 1) `(pi)/(2) n in I` ` 3 x = (4n+1)(pi)/(2)implies x=(4n+1)(pi)/(6)` `sin 7x= sin(4m+1)(pi)/(2), m in I` `x=(4m+1)(pi)/(14)` for common solution `(4n+1)(pi)/(6)=(4m+1)(pi)/(14)` Solving these `1=3m-7n` First solution ios m=5,n=2 Second solution is m=12,n=5 So two solutions are possible |
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