分析:(1)根據(jù)有理數(shù)的性質(zhì)去括號(hào)后直接加減運(yùn)算;
(2)利用乘方運(yùn)算,再結(jié)合有理數(shù)的加減運(yùn)算;
(3)利用乘方運(yùn)算,再結(jié)合有理數(shù)的加減乘除混和運(yùn)算;
(4)根據(jù)整式的運(yùn)算性質(zhì)首先找出同類(lèi)項(xiàng),即所含字母相同,而且相同字母的次數(shù)相同的是同類(lèi)項(xiàng),合并同類(lèi)項(xiàng)是,只是將同類(lèi)項(xiàng)的系數(shù)進(jìn)行加減運(yùn)算,字母不發(fā)生任何變化;
(5)(6)利用以上法則進(jìn)行運(yùn)算;
解答:解:(1)-20+(-14)-(-18)+13
=-20-14+18+13,
=-34+31,
=-3;
(2)-2
2+3×(-1)
4-(-4)×5
=-4+3+20,
=19;
(3)0.25×(-2)
3-[4÷(-
)
2+1]+(-1)
2009
=0.25×(-8)-(9+1)-1,
=-2-10-1,
=-13;
(4)3a
2+2a-4a
2-7a
=(3-4)a
2+(2-7)a,
=-a
2-5a;
(5)(4n-2n
2+2+6n
3)-3(n
2+2n
3-1+3n)
=4n-2n
2+2+6n
3-3n
2-6n
3+3-9n,
=(6-6)n
3+(-2-3)n
2+(4-9)n+5,
=-5n
2-5n+5;
(6)3x
2-[7x-3(4x-3)-2x
2]
=3x
2-(7x-12x+9-2x
2,
=3x
2-7x+12x-9+2x
2,
=(3+2)x
2+(-7+12)x-9,
=5x
2+5x-9.
點(diǎn)評(píng):此題主要考查了整式加減運(yùn)算,與有理數(shù)的混和運(yùn)算以及乘方運(yùn)算,運(yùn)算過(guò)程中特別注意運(yùn)算符號(hào)問(wèn)題.