Prove that acb if and only if anb a 2. if bca, prove that b a\ (a\b) 3. if f: a- b and e, fc a show that: a. f(euf) f(e) uf (f) b. f (enf)f(e)nf (f) 4. prove that: 13+23 +.+ n3 = [; n (n+ 1)]2 vn en (use mathematical induction)

Mexico city, mexico, is the world's second largest metropolis and is also one of its fastest-growing cities with a projected growth rate of 3.2% per year. its population in 1991 was 20,899,000 people. use the formula p = 20.899e0.032t to predict its population p in millions with t equal to the number of years after 1991. what is the predicted population to the nearest thousand of mexico city for the year 2010?

Some boys and girls were asked if they had a pet. one third of the group were boys. there were 20 boys. 20% of the girls had a pet. boys with a pet : girls with a pet = 1 : 5 i need to know how many girls there are.

What will the graph look like for a system of equations that has no solution? a. the lines will be perpendicular. b. the lines will cross at one point. c. both equations will form the same line. d. the lines will be parallel.