Question

[k(k+1)/12](3k^2+11k+10)+(k+1)(k+2) 怎么化简

Answer 1

3k^2+11k+10

=（3k+5）(k+2)

[k(k+1)/12](3k^2+11k+10)+(k+1)(k+2)

=[k(k+1)/12]（3k+5）(k+2)+(k+1)(k+2)

=(k+1)(k+2)[k(3k+5)/12+1]

=(k+1)(k+2)[k(3k+5)+12]/12

=(k+1)(k+2)(3k^2+5k+1)/12