(n+1)(n+2)
———————— = 210
2
(想要過程。謝謝。)
求n=?
(n+1)(n+2)
———————— = 210
2
(想要過程。謝謝。)
求n=?
n2+3n+2=420把420移到左边得n2+3n-418=0所以有(n-19)(n+22)=0
所以有n=19或 -22
(n+1)(n+2)=420
n^2+3n-418=0
n=19,n=-22