Solve by substitution method - 3x - y = 3, 9x - 3y = 9 [with Video] - Ex 3.2

part 2 - Ex 3.2, 1 (iii) - Ex 3.2 - Serial order wise - Chapter 3 Class 10 Pair of Linear Equations in Two Variables
part 3 - Ex 3.2, 1 (iii) - Ex 3.2 - Serial order wise - Chapter 3 Class 10 Pair of Linear Equations in Two Variables
part 4 - Ex 3.2, 1 (iii) - Ex 3.2 - Serial order wise - Chapter 3 Class 10 Pair of Linear Equations in Two Variables

 

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Ex 3.2, 1 Solve the following pair of linear equations by the substitution method. (iii) 3x – y = 3 9x – 3y = 9 3x – y = 3 9x – 3y = 9 Solving (1) 3x – y = 3 3x = y + 3 x = (𝒚 + 𝟑)/𝟑 Putting value of x in (2) 9x – 3y = 9 9((𝑦 + 3)/3)−3𝑦=9 3(y + 3) – 3y = 9 3y + 9 – 3y = 9 3y – 3y + 9 = 9 0 + 9 = 9 9 = 9 The statement is true for all values of x So, there are infinitely many solutions Reason :- The 2 equations given in question are 3x – y = 3 9x – 3y = 9 From (2), taking 3 common , we get 3 (3x – y) = 9 3x – y = 9/3 3x – y = 3 Which is equation same as equation (1) Hence both equation actually same So there can be infinite values of x and y So there can be infinite values of x and y For Example And so on If y = 1, 3x – 1 = 3 3x = 3 + 1 x = (1 + 3)/3 x = 4/3 If y = 2, 3x – 2 = 3 3x = 3 + 2 x = (2 + 3)/3 x = 5/3

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Davneet Singh has done his B.Tech from Indian Institute of Technology, Kanpur. He has been teaching from the past 14 years. He provides courses for Maths, Science and Computer Science at Teachoo