解:(1)
,
∵①+②×2得:11x=22,
x=2,
把x=2代入②得:y+8=7,
解得:y=-1,
∴原方程組的解為
;
(2)原式=3a
2+2b
4c
=3a
4b
4c;
(3)原式=(
)
2005×(-8)
2005×(-8)
=[
×(-8)]
2005×(-8)
=(-1)
2005×(-8)
=-1×(-8)
=8.
分析:(1)①+②×2得出11x=22,求出x,把x的值代入②得出y+8=7,求出y即可.
(2)根據(jù)單項式乘以單項式法則進(jìn)行計算即可.
(3)先根據(jù)同底數(shù)冪展開得出(
)
2005×(-8)
2005×(-8),根據(jù)積的乘方的逆運(yùn)用得出[
×(-8)]
2005×(-8),再求出即可.
點評:本題考查了解二元一次方程組,單項式乘以單項式,積的乘方和冪的乘方等知識點的應(yīng)用.