Question

运用公式计算 求解呀 速度呀 大侠们

Answer 1

497x503 =(500-3)(500+3) = 500^2-3^2= 250000-9=249991

997^2-998*996 =997^2-(997+1)(997-1)=997^2-(997^2-1^2)=1

(40+2/3)(40-2/3)= 40^2 -(2/3)^2 =1600 -4/9 =1599 5/9