Which of the following are trinomials?

How many different ways can you make change for $.50 using only nickels,dimes, and quarters?

1- what do you think the product of a nonzero rational number and an irrational number is? is it rational or irrational? make use of variables, the closure property of integers, and possibly a proof by contradiction to prove your hypothesis.2- why do we have to specify that the rational number must be nonzero when we determine what the product of a nonzero rational number and an irrational number is? if the rational number were 0, would it give us the same result we found in the first question?

Two years ago a man was six times as old as his daughter. in 18 years he will be twice as old as his daughter. determine their present ages.