1) =2p²+2q²+4pq-4pq+p²+q²=3p²+3q²
2)=( b²-a²)(b²+a²)=b⁴-a⁴
3)=n²-9t²+n²-4t²-2n²+13t²=0
-8х+(4+3х)=10-х