-1.6α + 2a^4 + 8.1a^3 In standard form

My options are
2a^4 + 8.1a + 1.6a

2a^4 - 1.6a + 8.1a^3

8.1a^3 + 2a^4 + 1.6a

Any help is appreciated greatly :)

Need solving this second acceleration problem.

Which expression gives you the distance between the points (5,1)and(9,-6)

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?