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Ex 4.3, 4 - Sum of reciprocals of Rehman ages, 3 years ago - Solving by Splitting the middle term - Statement given

Ex 4.3, 4 - Chapter 4 Class 10 Quadratic Equations - Part 2
Ex 4.3, 4 - Chapter 4 Class 10 Quadratic Equations - Part 3

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Ex 4.3 ,4 The sum of the reciprocals of Rehman s ages, (in years) 3 years ago and 5 years from now is 1/3 . Find his present age. Let Rehman's current age = x Rehman s age 3 years ago = x 3 Rehman s age 5 years from now = x + 5 Given that Sum of reciprocal of Rehman s ages 3 yr. ago and 5 yr. from now = 1/3 1/(( 3 )) + 1/(( 5 )) = 1/3 1/(x 3)+1/(x + 5)=1/3 (x + 5 + x 3)/((x 3)(x + 5))=1/3 (2x + 2)/((x 3)(x + 5))=1/3 (2x + 2) " " 3=1" " (x 3)(x+5) 6x + 6 = x(x + 5) 3 (x + 5) 6x + 6 = x2 + 5x 3x 15 0 = x2 + 5x 3x 15 6x 6 0 = x2 + 5x 3x 6x 15 0 = x2 4x 21 x2 4x 21 = 0 We factorize by splitting the middle term method x2 + 3x 7x 21 = 0 x (x + 3) 7 (x + 3) = 0 (x 7) (x + 3) = 0 So, x = 7 and x = -3 But x cannot be negative, as x is Rehman s current age So, x = 7 Rehman s current age = x = 7 years

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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 12 years. He provides courses for Maths, Science, Social Science, Physics, Chemistry, Computer Science at Teachoo.