# mathfunctions

1. ### Discrete Math-Functions

Problem: The multiplication of real numbers are functions mult: R x R to R, where mult(x,y)=xy. Is mult one-to-one? Is it onto?
2. ### discrete math:functions,recurrence relation

a) Let f:N*N->Q be defined by f(m,n)=(m-3)/n. Determine if f is injective or surjective. b) Show that if f:A->B and g:B->C are both bijective, then the composition (g o f):A->c is also bijective. Solve the recurrence relations a(r)-5a(r-1)+6a(r-2)=2^r+r (r,r-1,r-2 are all subscripts)