1. С.
2. а^4*b^6-16c^8=(a^2*b^3)^2-(4c^4)^2=(a^2*b^3-4c^4)(a^2*b^3+4c^4).
3. 0.25 а^2 -*ab + 9b^2=0,25a^2-2*0,5*3ab+9b^2=0,25a^2-3ab+9b^2.
4. (8+х)(8-х)+(х+2)^2=64-x^2+x^2+4x+4=4x+68.
5. m^2 + 2* + 0.04=m^2 + 2*m*0,2+0.04=m^2+0,4m+0,04.
6. (2-а)(4+2а+а^2)-(3+а)(9-6а+а^2)=8-a^3-(3+a)(3-a)^2=8-a^3-(9-a^2)(3-a)=8-a^3-(27-9a-3a^2+a^3)=8-a^3-27+9a+3a^2-a^3=-2a^3+3a^2+9a+8=-2*(-2)^3+3*(-2)^2+9*(-2)+8=16+12-18+8=18.