【参考答案】1、3m+6n=3(2x²+3xy-2x-1)+6(-x²+xy-1)=6x²+9xy-6x-3-6x²+6xy-6=(6x²-6x²）+（9xy+6xy)-6x-9=15xy-6x-9∴ y=02、x²-3x+1=0x-3+(1/x)=0∴ x+(1/x)=3∴ x²+ (1/x...