(iv) 3x + 2y + 11 = 0; 7x – 4y = 9
Sol. 3x + 2y + 11 = 0
∴ 3x + 2y = – 11
7x – 4y = 9
|
D
|
=
|
3
|
2
|
=
|
(3 × -4) – (7 × 2)
|
=
|
-12 – 14
|
=
|
-26
|
|
|
|
7
|
-4
|
|
|
|
|
|
|
|
DX
|
=
|
-11
|
2
|
=
|
(-11 × -4) – (9 × 2)
|
=
|
44 – 18
|
=
|
26
|
|
|
|
9
|
-4
|
|
|
|
|
|
|
|
DY
|
=
|
3
|
-11
|
=
|
(3 × 9) – (7 × -11)
|
=
|
27 + 77
|
=
|
104
|
|
|
|
7
|
9
|
|
|
|
|
|
|
By Cramer's rule,
|
x
|
=
|
Dx
|
=
|
26
|
=
|
-1
|
|
|
|
D
|
|
-26
|
|
|
|
y
|
=
|
Dx
|
=
|
104
|
=
|
-4
|
|
|
|
D
|
|
-26
|
|
|
∴ x = – 1 and y = – 4 is the solution of given
simultaneous equations.
