Chapter I : Linear Equations in two variables in two variables

Example 6: Solve for x and y:

Solution: putting x + y =u and x - y = v the given equation reduces to

Multiplying equation (1) by 4 and equation (2) by 3 we get

Subtracting (4) from (3) we get

11/u = 1

Or, u = 11

Or,

Putting u = 11 in (1) we get

Or,

Adding (5) and (6) we get

2x = 16

x = 8

Putting x = 8 in (5) we get

8 + y = 11

y = 3