Which functions are not one-to-one functions?

Identify the polynomial. a2b - cd3 a.monomial b.binomial c.trinomial d.four-term polynomial e.five-term polynomial

Expresa commuter train leaves downtown sation and travels at a average speed of 55 miles per hour towards the north side sation, which is 50miles away. thirty minutes later, express commuter train #7 leaves north side and travels at a average speed of 35miles per hour towards downtown sation. at the moment the two trains pass each other, how far(in miles) is train #12 from the downtown sation and how long(in minutes) has the #12 train been traveling

0if x and y vary inversely and y=6 as x=7, what is the constant of variation?