a student says "of course, it is easy to see that the expression of 3x^6+5x^3-7x^9 has three terms, a degree of 3 and a positive leading coefficient. part a: whether or not the student is correct, give a possible explanation in terms of the structure of the expression why the student might say that part b: is the student correct? explain part c: another student says: "assuming that x=1, the expression 3x^6+5x^3-7x^9 turns into an expression with one term as it is considered to be a zero degree polynomial." is this student correct? explain