Question

几道五年级简便计算.第一道（1+0.39+0.86)*(0.39+0.86+1.98)-(1+0.39+0.86+1.9

Answer 1

第一道（1+0.39+0.86)*(0.39+0.86+1.98)-(1+0.39+0.86+1.98)*(0.39+0.86)=把（1+0.39+0.86）设为A,（0.39+0.86)设为B=A*(B+1.98)-(A+1.98)*B=A*B+1.98*A-A*B-1.98*B=1.98*(A*B)=1.98*1=1.98第二道 2005*200620062006...