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整式的乘除和因式分解①2a²+a^8÷a^6②(-2ab)(-1/3a²b)+5ab×1/3a

来源:学生作业帮 编辑:作业帮 分类:数学作业 时间:2024/07/08 07:44:03
整式的乘除和因式分解
①2a²+a^8÷a^6②(-2ab)(-1/3a²b)+5ab×1/3a²b③(x-y+9)(x+y-9)④2011²-2008×2014⑤若(y+3)(y-2)=y²+my+n,求mn得值
①2a²+a^8÷a^6
=2a²+a²
=3a²
②(-2ab)(-1/3a²b)+5ab×1/3a²b
=2/3a³b²+5/3a³b²
=7/3a³b²
③(x-y+9)(x+y-9)
=[x-(y-9)][x+(y-9)]
=x²-(y-9)²
=x²-y²+18y-81
④2011²-2008×2014
=2011²-(2011-3)(2011+3)
=2011²-(2011²-3²)
=2011²-2011²+3²
=9
⑤若(y+3)(y-2)=y²+my+n,求mn得值
(y+3)(y-2)
=y²+y-6
∴m=1
n=-6
∴mn=-6