how to simplify k(k+1)(k+2)+3(k+1)(k+2) to (k+1)(k+2)(k+3)?

To simplify the given expression, first expand each term:

k(k+1)(k+2) + 3(k+1)(k+2)

= k(k^2 + 2k + 1) + 3(k^2 + 2k + 2)

= k^3 + 2k^2 + k + 3k^2 + 6k + 6

= k^3 + 5k^2 + 7k + 6

Now, to factor out the common terms and simplify further, notice that (k+1)(k+2) can be factored out of each term:

= (k+1)(k+2)(k) + 3(k+1)(k+2)

= (k+1)(k+2)(k + 3)

Therefore, the simplified expression is (k+1)(k+2)(k+3).