If `^n+5P_(n+1)=(11(n-1))/2^(n+3)P_n` , find `ndot`

Explanation

We have, `.^(n+5)C_(n+1)=(11(n-1))/(2)xx.^(n+3)P_(n)`
`implies((n+5)!)/(4!)=(11(n-1))/(2)xx((n+3)!)/(3!)`
`implies((n+5)(n+4))/(4)=(11(n-1))/(2)`
`impliesn^(2)-13n+42=0implies(n-6)(n-7)=0`
`impliesn=6` or n=7
The number of points of intersection of lines is `.^(6)C_(2)` or `.^(7)C`
`=15` or 21