Me. i don't understand at all what to do

Evaluate the dot product of (3,-1) and (1,5)

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?

15 there is a line that includes the point 0,10 and has a slope of 7/4. what is it’s equation in slope intercept form