x²-3x-18=0 using by completing the square
Answers
Answered by
3
Step-by-step explanation:
In this way:
x
2
+
3
x
−
18
=
0
⇒
x
2
+
3
x
+
(
3
2
)
2
−
(
3
2
)
2
−
18
=
0
⇒
(
x
2
+
3
x
+
9
4
)
−
9
4
−
18
=
0
⇒
(
x
+
3
2
)
2
=
18
+
9
4
⇒
(
x
+
3
2
)
2
=
72
+
9
4
⇒
(
x
+
3
2
)
2
=
81
4
⇒
x
+
3
2
=
±
9
2
⇒
x
=
−
3
2
±
9
2
⇒
x
1
=
−
3
2
−
9
2
=
−
12
2
=
−
6
x
2
=
−
3
2
+
9
2
=
6
2
=
3
.
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