Please help me prove the following about Lipschitz Constants

Let F : D CR~ ~ R~ satisfy FEC` ( D ) for an open convex set D CR". Suppose J ( ac ) , the Jacobian of Fat ac is Lipschitz continuous in D with Lipschitz constant I . ( a ) Show for u , u ED that | #` ( 0 ) - F ( 20 ) - J ( 20 ) ( 2 - 20)|1 {} 1/20 - 0 /1 2. N ( b) Show for u , U , ac ED that (( #` ( 0 ) - F` ( 20 ) - J ( 20 ) ( U - 20) 11