web analytics

Ex 4.3, 5 - In a class test, sum of Shefali marks in maths - Ex 4.3

  1. Chapter 4 Class 10 Quadratic Equations
  2. Serial order wise
Ask Download

Transcript

Ex 4.3 ,5 In a class test, the sum of Shefali’s marks in Mathematics and English is 30. Had she got 2 marks more in Mathematics and 3 marks less in English, the product of their marks would have been 210. Find her marks in the two subjects. Let shefali’s marks in mathematics = x Given that sum of Shefali’s marks in English and Mathematics is 30 ∴ Marks in mathematics + Marks in English = 30 x + Marks in English = 30 Marks in English = 30 – x Also, it is given that had she got 2 marks more in mathematics and 3 marks less in English, the product of their marks would have been 210 ∴ (Marks in Maths + 2) × (Marks in English – 3) = 210 (x + 2) (30 – x – 3) = 210 (x + 2) (27 – x ) = 210 x (27 – x) + 2 (27 – x) = 210 27x – x2 + 54 – 2x = 210 27x – x2 + 54 – 2x – 210 = 0 – x2 – 2x + 27x + 54 – 210 = 0 – x2 + 25x – 156 = 0 0 = x2 – 25x + 156 x2 – 25x + 156 = 0 We factorize by splitting the middle term method x2 – 12x – 13x + 156 = 0 x (x – 12) – 13 (x – 12) = 0 (x – 13) (x – 12) = 0 Therefore x = 13, x = 12 are the roots of the given equation Assuming x = 12, Marks in maths = x = 12 Marks in English = 30 – x = 30 – 12 = 18

About the Author

Davneet Singh's photo - Teacher, Computer Engineer, Marketer
Davneet Singh
Davneet Singh is a graduate from Indian Institute of Technology, Kanpur. He provides courses for Mathematics from Class 9 to 12. You can ask questions here.
Jail