(1)A-2(-4a²+6ab+7)=7a²-7abA=7a²-7ab+2(-4a²+6ab+7)A=7a²-7ab-8a²+12ab+14A=-a²+5ab+14(2)|a+1|+|b-2|=0a=-1,b=2A=-1+5*(-1)*2+14=-1-10+14=3