UC知道奥数题：（3.15+2.17+5.61）*（2.17+5.61+6.6）—（3.15+2.17+5.61+6.6）*（2.17+5.61）
来源：百度知道 编辑：UC知道 时间：2024/05/25 00:45:16
要求详细过程
（3.15+2.17+5.61）*（2.17+5.61+6.6）—（3.15+2.17+5.61+6.6）*（2.17+5.61）
=（3.15+2.17+5.61）*（2.17+5.61+6.6）—（3.15+2.17+5.61）*（2.17+5.61）—6.6*（2.17+5.61）
=(3.15+2.17+5.61)(2.17+5.61+6.6-2.17-5.61)—6.6*（2.17+5.61）
=(3.15+2.17+5.61)*6.6-6.6*（2.17+5.61）
=6.6*(3.15+2.17+5.61-2.17-5.61）
=6.6*3.15
=20.79
设：3.15+2.17+5.61=A
2.17+5.61=B
原式=A*（B+6.6）-（A+6.6）*B
=A*B+6.6*A-A*B-6.6*B
=6.6*（A-B）
∵A-B=（3.15+2.17+5.61）-（2.17+5.61）=3.15
∴6.6*（A-B）=6.6*3.15=20.79