what is (k+h)^3 when it is expanded?

(k + h)³  =  (k + h)[(k + h)²]  = (k + h)[k² + 2kh + h²]

                = k³  + 2k²h + kh² + hk² + 2kh² + h³ 

                = k³  + 3k²h + 3kh² + h³ 

You may want to check out Pascal's Triangle on the net, or ask your teacher for a quicker way.