Question

By applying substitution and elimination ways, find solution of the following linear equations:
3x + y = 7
5x - 3y = 7

Answer 1

3x + y = 7 ...(1)

5x - 3y = 7 ...(2)

By Elimination Method

Multiplying eqn.(1) by 3

9x + 3y = 21 ...(3)

Adding eqn (2) and (3)

14x = 28

x = 2.

Substituting value if x in eqn (1)

3(2) + y = 7

6 + y = 7

y = 1.

By Substitution Method

Considering eqn (1),

3x + y = 7

or, y = 7 - 3x...(4)

Substituting (4) in eqn (2)

5x - 3(7-3x) = 7

5x -21 + 9x = 7

14x = 28

x = 2.

Substituting value of x in eqn (4)

y = 7-3(2)

or, y = 7-6

or, y = 1.

Finally, we get x=2 and y=1.