Answer:
1. a²+10a+25
2.9x²y²-42xy+49
3. x²+y²-4y+2xy+4
4.4x²+9y²+20x+30y+12xy+25
5.9a²+b²+4c²-6ab+12ac-4bc
6.16-4x²
7.9x²y²-a²b²c²
8.x*-16y4
9.-x²+2x+3
10.x²-y²+4x-2y+3
11.
12.x-9x4+27x²-27
13.8x³+60x²+150x+125
14.x³-3x²y+3xy²-y³+3x²-6xy+3y²+3x+1 15.x³+3x²y-6x²+3xy²-12xy+12x+y³-6y²+12y
-8