Find the difference of the polynomials given below and classify it in terms of degree and number of terms. 3n^2(n^2+4n-5) - (2n^2-n^4+3)

To get the difference we proceed as follows:
3n^2(n^2+4n-5) - (2n^2-n^4+3)
open the parenthesis
3n²×n²+3n²×4n-3n²×5-2n²+n⁴-3
this will give us:
3n⁴+12n³-15n²-2n²+n⁴-3
putting like terms together 
3n⁴+n⁴+12n³-15n²-2n²-3
simplifying further we obtain
4n⁴+12n³-17n²-3

b] The highest degree of the the result will be obtained by considering the term with the highest power. The highest power is 4, thus the result will be classified as polynomial of degree 4.