Question

Solve the following pair of linear equations by the substitution method:
1. 3x-y=3
9x-3y=9

Please solve it in a book with calculations.

Answer 1

3x - y = 3-----------(1)
9x - 3y = 9 -------(2)

from equation (2)
3( 3x - y) = 3 × 3

3x - y = 3 ----------(2)
now , compare both equations (1) and (2)
you see , both are same equation no change any term . hence here we can say that both are consistent .so, infinity solution exist here.

by the way you want substitution method
right??
Sol :-
3x - y = 3 --------(1)
9x -3y = 9------(2)

from eqn (1)

y = 3x -3 , put this in equation (2)

9x - 3(3x - 3 ) = 9

9x - 9x + 9 = 9

9 = 9
LHS = RHS

this is true for all real value so,
solution is infinity