123的平方-122*118
=123^2-(120+2)*(120-2)(平方差公式)
=123^2-(120^2-2^2)
=123^2-120^2+2^2
=(123+120)*(123-120)+4(平方差公式)
=143*3+4
=729+4
=733
123的平方-122*118
=123^2-(120+2)(120-2)
=123^2-120^2 +2^2
=(123+120)(123-120)+4
=243*3+4
=729+4
=733
123的平方-122*118=123*123-(123-1)*118
=123*123-123*118+118
=(123-118)*123+118
=5*123+118
=733
123²-122*118
=123²-(123-1)(123-5)
=123²-123²+6*123-5
=733
123的平方-122*118=123^2-(123-1)(123-5)=123*6-5=733