2.先化简再求值.(1)3x²-8x+x³-12x²-3x³+1 其中x=2(2)4x²+2xy+9y²-2x²-3xy+y² x=2,y=1
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![2.先化简再求值.(1)3x²-8x+x³-12x²-3x³+1 其中x=2(2)4x²+2xy+9y²-2x²-3xy+y² x=2,y=1](/uploads/image/z/1690634-2-4.jpg?t=2.%E5%85%88%E5%8C%96%E7%AE%80%E5%86%8D%E6%B1%82%E5%80%BC.%EF%BC%881%EF%BC%893x%26%23178%3B%EF%BC%8D8x%EF%BC%8Bx%26%23179%3B%EF%BC%8D12x%26%23178%3B%EF%BC%8D3x%26%23179%3B%EF%BC%8B1+%E5%85%B6%E4%B8%ADx%EF%BC%9D2%EF%BC%882%EF%BC%894x%26%23178%3B%EF%BC%8B2xy%EF%BC%8B9y%26%23178%3B%EF%BC%8D2x%26%23178%3B%EF%BC%8D3xy%EF%BC%8By%26%23178%3B+x%EF%BC%9D2%2Cy%EF%BC%9D1)
2.先化简再求值.(1)3x²-8x+x³-12x²-3x³+1 其中x=2(2)4x²+2xy+9y²-2x²-3xy+y² x=2,y=1
2.先化简再求值.
(1)3x²-8x+x³-12x²-3x³+1 其中x=2
(2)4x²+2xy+9y²-2x²-3xy+y² x=2,y=1
2.先化简再求值.(1)3x²-8x+x³-12x²-3x³+1 其中x=2(2)4x²+2xy+9y²-2x²-3xy+y² x=2,y=1
(1)3x²-8x+x³-12x²-3x³+1 其中x=2
原式=(1-3)x³+(3-12)x²-8x+1
=-2x³-9x²-8x+1
当x=2
原式=-2*(2)³-9*(2)²-8*2+1
=-2*8-9*4-16+1
=-16-36-16+1
=-32-36+1
=-67
(2)4x²+2xy+9y²-2x²-3xy+y² x=2,y=1
原式=(4-2)x²+(9+1)y²+(2-3)xy
=2x²+10y²-xy
当x=2,y=1
原式=2*(2)²+10*(1)²-2*1
=2*4+10-2
=16
-2x^3-9x^2-8x+1=-16-36-16+1=-67 2x^2-xy+10y^2=8-2+10=16 望采纳纯手打