已知M=3a^3-10a^2-5,N=-2a^3+5-10a,P=7-5a-2a^2,求M+2N-3P和M-3N+2P的值

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已知M=3a^3-10a^2-5,N=-2a^3+5-10a,P=7-5a-2a^2,求M+2N-3P和M-3N+2P的值
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已知M=3a^3-10a^2-5,N=-2a^3+5-10a,P=7-5a-2a^2,求M+2N-3P和M-3N+2P的值
已知M=3a^3-10a^2-5,N=-2a^3+5-10a,P=7-5a-2a^2,求M+2N-3P和M-3N+2P的值

已知M=3a^3-10a^2-5,N=-2a^3+5-10a,P=7-5a-2a^2,求M+2N-3P和M-3N+2P的值
M+2N-3P
=2(3a³-10a²-5)+2(-2a³+5-10a)-3(7-5a-2a²)
=6a³-20a²-10-4a³+10-20a-21+15a+6a²
=2a³-14a²-5a-21
M-3N+2P
=2(3a³-10a²-5)-3(-2a³+5-10a)+2(7-5a-2a²)
=6a³-20a²-10+6a³-15+30a+14-10a-4a²
=12a³-24a²+20a-11