Chapter 4: Quadratic Equations

Example – 15. 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.

Solution :- Let her marks in Mathematics = x, then marks in English = 30 – x.
As per statements, her marks in Mathematics = x + 2

d her marks in English = 30 – x – 3 = 27 – x
A/Q                 (x + 2)(27 – x) = 210
Or,                  27x – x2 + 54 – 2x = 210
Or,                  x2 – 25x + 156 = 0
Or,                  (x – 12)(x – 13) = 0 
Either,        x – 12 = 0, Or, x – 13 = 0

Thus, x = 12, 13 

Hence, either marks in Mathematics = 12 & marks in English = 18,

Or, marks in Mathematics = 13 & marks in English = 17.

 

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Subjects Maths (Part-1) by Mr. M. P. Keshari
Chapter 1 Linear Equations in Two Variables
Chapter 2 HCF and LCM
Chapter 3 Rational Expression
Chapter 4 Quadratic Equations
Chapter 5 Arithmetic Progressions
Chapter 6 Instalments
Chapter 7 Income Tax
Chapter 8 Similar Triangles