Question

下列运算正确的是（　　）                                                                     

A．5m+2m=7m²           B．﹣2m²m³=2m⁵                                            

C．（﹣a²b）³=﹣a⁶b³  D．（b+2a）（2a﹣b）=b²﹣4a²                           

Answer 1

C【考点】幂的乘方与积的乘方；合并同类项；单项式乘单项式；平方差公式．                  

【分析】A、依据合并同类项法则计算即可；B、依据单项式乘单项式法则计算即可；C、依据积的乘方法则计算即可；D、依据平方差公式计算即可．                                                                     

【解答】解：A、5m+2m=（5+2）m=7m，故A错误；                                   

B、﹣2m²m³=﹣2m⁵，故B错误；                                                            

C、（﹣a²b）³=﹣a⁶b³，故C正确；                                                         

D、（b+2a）（2a﹣b）=（2a+b）（2a﹣b）=4a²﹣b²，故D错误．                 

故选：C．                                                                                         

【点评】本题主要考查的是整式的计算，掌握合并同类项法则、单项式乘单项式法则、积的乘方法则以及平方差公式是解题的关键．