Solve the following pair of linear equations by substitution method:

1.	Solve the following pair of linear equations by substitution method: 3x – y = 3; 9x - 3y = 9
Answer» Given equations are 3x – y = 3 …(i) 9x – 3y = 9 …(ii) From eqⁿ (i), y = 3x – 3 …(iii) On substituting y = 3x – 3 in eqⁿ (ii), we get ⇒ 9x – 3(3x – 3) = 9 ⇒ 9x – 9x + 9 = 9 ⇒ 9 = 9 This equality is true for all values of x, therefore given pair of equations have infinitely many solutions.

Solve the following pair of linear equations by substitution method: 3x – y = 3; 9x - 3y = 9

Answer»

Given equations are

3x – y = 3 …(i)

9x – 3y = 9 …(ii)

From eqⁿ (i), y = 3x – 3 …(iii)

On substituting y = 3x – 3 in eqⁿ (ii), we get

⇒ 9x – 3(3x – 3) = 9

⇒ 9x – 9x + 9 = 9

⇒ 9 = 9

This equality is true for all values of x, therefore given pair of equations have infinitely many solutions.