Respuesta :

1 Simplify
n
(
n

1
)
(
n

2
)
×
1
n(n−1)(n−2)×1 to
n
(
n

1
)
(
n

2
)
n(n−1)(n−2)
n
=
n
(
n

1
)
(
n

2
)
n=n(n−1)(n−2)

2 Expand
n
=
n
3

2
n
2

n
2
+
2
n
n=n
​3
​​ −2n
​2
​​ −n
​2
​​ +2n

3 Simplify
n
3

2
n
2

n
2
+
2
n
n
​3
​​ −2n
​2
​​ −n
​2
​​ +2n to
n
3

3
n
2
+
2
n
n
​3
​​ −3n
​2
​​ +2n
n
=
n
3

3
n
2
+
2
n
n=n
​3
​​ −3n
​2
​​ +2n

4 Move all terms to one side
n

n
3
+
3
n
2

2
n
=
0
n−n
​3
​​ +3n
​2
​​ −2n=0

5 Simplify
n

n
3
+
3
n
2

2
n
n−n
​3
​​ +3n
​2
​​ −2n to

n

n
3
+
3
n
2
−n−n
​3
​​ +3n
​2
​​

n

n
3
+
3
n
2
=
0
−n−n
​3
​​ +3n
​2
​​ =0

6 Factor out the common term
n
n

n
(
1
+
n
2

3
n
)
=
0
−n(1+n
​2
​​ −3n)=0

7 Multiply both sides by

1
−1
n
(
1
+
n
2

3
n
)
=
0
n(1+n
​2
​​ −3n)=0

8 Solve for
n
n
n
=
0
n=0

9 Apply the Quadratic FormulaHow?
n
=
3
+
5
2
,
3

5
2
n=
​2

​3+√
​5

​​
​​ ,
​2

​3−√
​5

​​
​​

10 Collect all solutions from the previous steps
n
=
0
,
3
+
5
2
,
3

5
2
n=0,
​2

​3+√
​5

​​
​​ ,
​2

​3−√
​5

​​
​​

Done