(Q3).Solve each pair of equations by using the substitution method.

x + 2y = – 1

2x – 3y = 12

Given: x + 2y = -1 ……. (1)

2x – 3y = 12 …….. (2)

From equation (1)x + 2y = -1

⇒ x = – – y

Substituting x = – – y in equation (2), we get

2 (- – y) – 3y = 12

– – y – 3y = 12

– – y = 12

y = – – 12

∴ y =
-
 = -.

Substituting y = – in equation (1), we get

x + 2 (- ) = – 1

x = – 1 +

x =

∴ The solution is (, – )