Pattern:
1.the sum of the squares of the first,second,and last terms
2.twice the product of the first and second terms
3.twice the product of the first and last terms.
4.twice the product of the second and last terms
Answers:
1.r²+t²+n²-2rt+2nr-2nt
2.e²+4a²+q²+4e²a²+2eq+4aq
Repeat the pattern to answer the others.