Question

Solve the following simultaneous equation:
$4x+5y=10;5x+4y=17$

• A. $x=3y=2$
• B. $x=1y=4$
• C. $x=0y=3$
• D. $x=5y=-2$

Answer 1

The correct option is D $x=5y=-2$

$4x+5y=10$ .....(1)

$5x+4y=17$ .......(2)

Adding (1) and (2). we get

$9x+9y=27$

$\Rightarrow x+y=3$ ......(3)

Now, subtracting (1) from (2). we get,

$x-y=7$ .......(4)

Adding (3) and (4). we get

$2x=10$

$\Rightarrow x=5$

Now, subtracting (3) from (4). we get,

$-2y=4$

$\Rightarrow y=-2$

$\therefore x=5,y=-2$

Option D is correct.