199.199*198-198.198*199的简

199.199*198-198.198*199的简便运算 18.9*178.178 +0.49-17.8*189.189

1个回答

199.199*198-198.198*199=(199+0.199)*198-(198+0.198)*199=199*198+0.199*0.198-198*199-0.198*0.198=0
18.9*178.178 +0.49-17.8*189.189 =18.9*(178+0.178) +0.49-17.8*(189+0.189)=18.9*178+18.9*0.178+0.49-17.8*189-17.8*0.189 =0.49
呵呵,就是这样子,答案没问题的话要采纳哦~谢谢