Answer: 5th degree binomial
Note: You can say it's a quintic binomial but I find its easier to go with "5th degree" instead of "quintic"
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How to get this answer:
The degree is the largest exponent for single variable polynomials such as this one. We see that 5 is the largest exponent, so the degree is 5. We consider this a quintic polynomial (think "quintuplets" which is how I remember). Though to be fair, the term "quintic" isn't used too much. Any degree larger than 4 you just state the number followed by "st", "nd", or "th" which is easiest I think.
This is a binomial because it has 2 terms. The terms are separated by a minus sign or subtraction sign. We can think of it as adding a negative
17n^5 - n^4 = 17n^5 + (-n^4)
The two terms 17n^5 and -n^4 are separated by a plus sign.
In general, terms of a polynomial are separated by either a plus sign or a minus sign.