N(n+5)-(n-3)(n+2) при n=2

Question

N(n+5)-(n-3)(n+2) при n=2

Answer 1

N(n+5)-(n-3)(n+2)=n²+5n-(n²-n-6)=n²+5n-n²+n+6=6n+6=6(n+1)
n=2  6(2+1)=6*3=18