2a+1与1+2a的值互为相反数,则2a+1+1+2a=0,则4a=-2,则a=-2分之1
-6x+16与7x-18的值互为相反数,则-6x+16+7x-18=0,则x=2,则x的平方-2x-2=4-4-2=-2