Given:
![n(n+1)=210](https://img.qammunity.org/2023/formulas/mathematics/college/kuy75p4kvzugijplcm2ebtwzr782qyzxhc.png)
Sol:.
![\begin{gathered} n(n+1)=210 \\ n^2+n=210 \\ n^2+n-210=0 \end{gathered}](https://img.qammunity.org/2023/formulas/mathematics/college/andz8n08j759a7gsik186sb8pakj6zqa2r.png)
![\begin{gathered} n^2+n-210=0 \\ n^2+15n-14n-210=0 \\ n(n+15)-14(n+15)=0 \\ (n+15)(n-14)=0 \\ n=-15,14 \end{gathered}](https://img.qammunity.org/2023/formulas/mathematics/college/ly96hz75y0yib1ooylb1vgyswd0dhizkxt.png)
The product of two negative number that mean number is negative.
![\begin{gathered} n=-15 \\ \end{gathered}](https://img.qammunity.org/2023/formulas/mathematics/college/33m6zqdxtkf4ki652dpk9kkewe3d46n6p9.png)
Then another number is:
![\begin{gathered} n+1=-15+1 \\ =-14 \end{gathered}](https://img.qammunity.org/2023/formulas/mathematics/college/kpv3dbfhljjvlbx0wfk55g5m9ygl2zw86u.png)
Number is -15,-14
Product of two negative consecutive number that mean if one number is "n" then another number is "n+1" and where n is a neagtive number so the value of "n" accept only negative value.
Consecutive number is define as a alternet number if the one number is "n" then another is may be "n+1" or "n-1".