# Example 13

Last updated at June 22, 2017 by Teachoo

Last updated at June 22, 2017 by Teachoo

Transcript

Example 13 The sum of a two-digit number and the number obtained by reversing the digits is 66. If the digits of the number differ by 2, find the number. How many such numbers are there? Number is of the form Let digit at units place = y and the digit at tens place = x Given that (Number) + (Reversed Number) = 66 (10x + y) + (10y + x) = 66 10x + x + 10y + y = 66 11x + 11y = 66 11(x + y) = 66 x + y = 66/11 x + y = 6 Also, given that digits of the number differ by 2, So x – y = 2 or y – x = 2 Solving equation (1) & (2) x + y = 6 …(1) x – y = 2 …(2) By elimination method –2y = –4 y = (−4)/(−2) y = 2 Putting y = 2 in (2) x – y = 2 x – 2 = 2 x = 4 Hence x = 4, y = 2 is the solution of equations (1) & (2) Thus, the number is = 10x + y = 10 (4) + 2 = 40 + 2 = 42 Solving equation (1) & (3) x + y = 6 …(1) y – x = 2 …(3) Solving (1) & (3) by elimination 2x = 4 x = 4/2 x = 2 Putting x = 2 in equation (3) y – x = 2 y – 2 = 2 y = 2 + 2 y = 4 Hence x = 2, y = 4 is the solution of equations (1) & (2) Thus, the number is = 10x + y = 10 (2) + 4 = 20 + 4 = 24 So, the numbers which satisfy the given equations are 24 & 42

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Class 10

Important Questions for Exam - Class 10

- Chapter 1 Class 10 Real Numbers
- Chapter 2 Class 10 Polynomials
- Chapter 3 Class 10 Pair of Linear Equations in Two Variables
- Chapter 4 Class 10 Quadratic Equations
- Chapter 5 Class 10 Arithmetic Progressions
- Chapter 6 Class 10 Triangles
- Chapter 7 Class 10 Coordinate Geometry
- Chapter 8 Class 10 Introduction to Trignometry
- Chapter 9 Class 10 Some Applications of Trignometry
- Chapter 10 Class 10 Circles
- Chapter 11 Class 10 Constructions
- Chapter 12 Class 10 Areas related to Circles
- Chapter 13 Class 10 Surface Areas and Volumes
- Chapter 14 Class 10 Statistics
- Chapter 15 Class 10 Probability

About the Author

Davneet Singh

Davneet Singh is a graduate from Indian Institute of Technology, Kanpur. He has been teaching from the past 8 years. He provides courses for Maths and Science at Teachoo. You can check his NCERT Solutions from Class 6 to 12.