Ignore what i chose: w/ a really easy probability problem

What is the point-slope form of theequation for the line with a slope of-2 that passes through (1, 4)? a y + 1 = -2(x + 4)b y-1=-2(x-4)c y + 4 = -2(x + 1)d y - 4 = -2(x - 1)

Which of the following is the true for f(x) = 5cos

1- is the product of two rational numbers irrational or rational? first, make a hypothesis by multiplying two rational numbers. then, use variables such as x=a/b and y=c/d and the closure property of integers to prove your hypothesis. 2- 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. 3- 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 part b?