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

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
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

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

①3a^2 . ②7/3a . ③x^2-y^2+18y-81. ④2011^2-(2011-3)(2011+3)=2011^2-2011^2+9=9. ⑤y^2+y-6=y^2+my+n. y=my. -6=n. m=1. n=-6. mn=-6.