题目内容
若M=x3-3x2y+xy2,N=x3-2xy2+1,则2x3+3x2y-7xy2+3等于
- A.N-5M
- B.M+N
- C.N-M
- D.3N-M
D
若M=x3-3x2y+xy2,N=x3-2xy2+1,则3N-M=3(x3-2xy2+1)-(x3-3x2y+xy2)=3x3-6xy2+3-x3+3x2y-xy2=2x3+3x2y-7xy2+3
若M=x3-3x2y+xy2,N=x3-2xy2+1,则3N-M=3(x3-2xy2+1)-(x3-3x2y+xy2)=3x3-6xy2+3-x3+3x2y-xy2=2x3+3x2y-7xy2+3
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