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Sum of the reciprocals of a man's age (in years) 5 years ago and 4 years from now is29190Find his present age. |
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Answer» Let the man's age be AHis age 5 years ago will be A - 5His age 4 years from now will be A + 4 [ 1 / (A - 5) ] + [ 1 / (A + 4) ] = 29 / 190[ (A + 4) + (A - 5) ] / [ (A - 5)x(A + 4) ] = 29 / 190(2A - 1) / (A² + 4A - 5A - 20) = 29 / 190190 x (2A - 1) = 29 x (A² + 4A - 5A - 20)380A - 190 = 29 x (A² - A - 20)380A - 190 = 29A² - 29A - 580380A + 29A - 190 + 580 = 29A²409A + 390 = 29A²29A² - 409A - 390 = 0 By solving equation , A = 15 years |
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