3x + 2y + 11 = 0; 7x – 4y = 9

(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.

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