问题
解答题
化简求值:3x3-2x2-[7-2x-(-x2-3x3)],其中x=-
|
答案
∵x=-
,1 2
∵原式=3x3-2x2-[7-2x+x2+3x3]
=3x3-2x2-7+2x-x2-3x3
=-3x2+2x-7,
当x=-
时,1 2
原式=-3x2+2x-7
=-3×(-
)2+2×(-1 2
)-71 2
=-
-1-73 4
=-
.35 4
化简求值:3x3-2x2-[7-2x-(-x2-3x3)],其中x=-
|
∵x=-
,1 2
∵原式=3x3-2x2-[7-2x+x2+3x3]
=3x3-2x2-7+2x-x2-3x3
=-3x2+2x-7,
当x=-
时,1 2
原式=-3x2+2x-7
=-3×(-
)2+2×(-1 2
)-71 2
=-
-1-73 4
=-
.35 4