Question

Solve the equations using graphical method: $x-y=3$ and $x+y=11$

• A. $(7,4)$
• B. $(-7,3)$
• C. $(7,-4)$
• D. $(-7,4)$

Answer 1

Answer: (A)

$(7,4)$

$x-y=3$ ----- (1)
$x+y=11$ ----- (2)
From equation (1)
$y=x-3$ ------ (3)
Assume the value of $x=6,7$ and put those values in equation (3)
If $x=6,y=6-3\Rightarrow y=3$
If $x=7,y=7-3\Rightarrow y=4$
On the above basis, the following points are:

x	6	7
y	3	4

Now plotting $(6,3),(7,4)$ and joining them, we get a straight line.
From equation (2),
$x+y=11$
$y=11-x$ ------ (4)
Assume the value of $x=6,7$ and put those values in equation (3)
If $x=6,y=11-6\Rightarrow y=5$
If $x=7,y=11-7\Rightarrow y=4$
Now table the following points:

x	6	7
y	5	4

Plotting $(6,5),(7,4)$ and joining them, we get another straight line.
These lines intersect at the point (7, 4) and therefore the solution of the equation is $x=7,y=4$ .