Question

For solving the following simultaneous equations by Cramer's rule, find the value of D_x and D_y : 3x - y = 7;
x + 4y = 11 

Answer 1

The given equations are 

3x - y = 7 .....eq (i)

x + 4y = 11 .....eq (ii)

`"D"_"x" = |(7,-1),(11,4)|`

= 7 × 4 - 11 × -1

= 28 + 11

D_x = 39

`"D"_"y" = |(3,7),(1,11)|`

= 3 × 11 - 1 × 7

= 33 - 7

D_y = 26