(
x
,
y
)
=
(
3
5
,
4
1
5
)
or
(
x
,
y
)
=
(
−
3
,
−
3
)
Explanation:
Given
[1]
XXX
y
−
2
x
=
3
[2]
XXX
x
2
+
y
2
=
18
Re-writing [1]
[3]
XXX
y
=
2
x
+
3
Substituting
(
2
x
+
3
)
from [3] for
y
in [2]
[4]
XXX
x
2
+
(
2
x
+
3
)
2
=
18
Simplifying
[5]
XXX
x
2
+
4
x
2
+
12
x
+
9
=
18
[6]
XXX
5
x
2
+
12
x
−
9
=
0
Factoring
[7]
XXX
(
5
x
−
3
)
(
x
+
3
)
=
0
⇒
x
=
3
5
or
x
=
−
3
case 1:
x
=
3
5
Substituting
3
5
for
x
in [3]
XXX
y
=
2
(
3
5
)
+
3
=
4
1
5
case 2:
x
=
−
3
Substituting
(
−
3
)
for
x
in [3]
XXX
y
=
2
(
−
3
)
+
3
=
−
3
